diff --git a/.ci/scripts/postgres_exec.py b/.ci/scripts/postgres_exec.py
deleted file mode 100755
index 0f39a336d52d..000000000000
--- a/.ci/scripts/postgres_exec.py
+++ /dev/null
@@ -1,31 +0,0 @@
-#!/usr/bin/env python
-# Copyright 2019 The Matrix.org Foundation C.I.C.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-import sys
-
-import psycopg2
-
-# a very simple replacment for `psql`, to make up for the lack of the postgres client
-# libraries in the synapse docker image.
-
-# We use "postgres" as a database because it's bound to exist and the "synapse" one
-# doesn't exist yet.
-db_conn = psycopg2.connect(
-    user="postgres", host="localhost", password="postgres", dbname="postgres"
-)
-db_conn.autocommit = True
-cur = db_conn.cursor()
-for c in sys.argv[1:]:
-    cur.execute(c)
diff --git a/.ci/scripts/test_old_deps.sh b/.ci/scripts/prepare_old_deps.sh
similarity index 71%
rename from .ci/scripts/test_old_deps.sh
rename to .ci/scripts/prepare_old_deps.sh
index 478c8d639ae8..7e4f060b17b8 100755
--- a/.ci/scripts/test_old_deps.sh
+++ b/.ci/scripts/prepare_old_deps.sh
@@ -5,18 +5,8 @@
 # - creates a venv with these old versions using poetry; and finally
 # - invokes `trial` to run the tests with old deps.
 
-# Prevent tzdata from asking for user input
-export DEBIAN_FRONTEND=noninteractive
-
 set -ex
 
-apt-get update
-apt-get install -y \
-        python3 python3-dev python3-pip python3-venv pipx \
-        libxml2-dev libxslt-dev xmlsec1 zlib1g-dev libjpeg-dev libwebp-dev
-
-export LANG="C.UTF-8"
-
 # Prevent virtualenv from auto-updating pip to an incompatible version
 export VIRTUALENV_NO_DOWNLOAD=1
 
@@ -33,12 +23,6 @@ export VIRTUALENV_NO_DOWNLOAD=1
 #   a `cryptography` compiled against OpenSSL 1.1.
 # - Omit systemd: we're not logging to journal here.
 
-# TODO: also replace caret bounds, see https://python-poetry.org/docs/dependency-specification/#version-constraints
-# We don't use these yet, but IIRC they are the default bound used when you `poetry add`.
-# The sed expression 's/\^/==/g' ought to do the trick. But it would also change
-# `python = "^3.7"` to `python = "==3.7", which would mean we fail because olddeps
-# runs on 3.8 (#12343).
-
 sed -i \
    -e "s/[~>]=/==/g" \
    -e '/^python = "^/!s/\^/==/g' \
@@ -55,7 +39,7 @@ sed -i \
 # toml file. This means we don't have to ensure compatibility between old deps and
 # dev tools.
 
-pip install --user toml
+pip install toml wheel
 
 REMOVE_DEV_DEPENDENCIES="
 import toml
@@ -69,8 +53,8 @@ with open('pyproject.toml', 'w') as f:
 "
 python3 -c "$REMOVE_DEV_DEPENDENCIES"
 
-pipx install poetry==1.1.14
-~/.local/bin/poetry lock
+pip install poetry==1.2.0
+poetry lock
 
 echo "::group::Patched pyproject.toml"
 cat pyproject.toml
@@ -78,6 +62,3 @@ echo "::endgroup::"
 echo "::group::Lockfile after patch"
 cat poetry.lock
 echo "::endgroup::"
-
-~/.local/bin/poetry install -E "all test"
-~/.local/bin/poetry run trial --jobs=2 tests
diff --git a/.ci/scripts/test_export_data_command.sh b/.ci/scripts/test_export_data_command.sh
index 033fd3e24e09..9f6c49acff73 100755
--- a/.ci/scripts/test_export_data_command.sh
+++ b/.ci/scripts/test_export_data_command.sh
@@ -32,7 +32,7 @@ else
 fi
 
 # Create the PostgreSQL database.
-poetry run .ci/scripts/postgres_exec.py "CREATE DATABASE synapse"
+psql -c "CREATE DATABASE synapse"
 
 # Port the SQLite databse to postgres so we can check command works against postgres
 echo "+++ Port SQLite3 databse to postgres"
diff --git a/.ci/scripts/test_synapse_port_db.sh b/.ci/scripts/test_synapse_port_db.sh
index b07a6b5d0862..8cc41d3dca4f 100755
--- a/.ci/scripts/test_synapse_port_db.sh
+++ b/.ci/scripts/test_synapse_port_db.sh
@@ -2,27 +2,27 @@
 #
 # Test script for 'synapse_port_db'.
 #   - configures synapse and a postgres server.
-#   - runs the port script on a prepopulated test sqlite db
-#   - also runs it against an new sqlite db
+#   - runs the port script on a prepopulated test sqlite db. Checks that the
+#     return code is zero.
+#   - reruns the port script on the same sqlite db, targetting the same postgres db.
+#     Checks that the return code is zero.
+#   - runs the port script against a new sqlite db. Checks the return code is zero.
 #
 # Expects Synapse to have been already installed with `poetry install --extras postgres`.
 # Expects `poetry` to be available on the `PATH`.
 
-set -xe
+set -xe -o pipefail
 cd "$(dirname "$0")/../.."
 
 echo "--- Generate the signing key"
-
-# Generate the server's signing key.
 poetry run synapse_homeserver --generate-keys -c .ci/sqlite-config.yaml
 
 echo "--- Prepare test database"
-
-# Make sure the SQLite3 database is using the latest schema and has no pending background update.
+# Make sure the SQLite3 database is using the latest schema and has no pending background updates.
 poetry run update_synapse_database --database-config .ci/sqlite-config.yaml --run-background-updates
 
 # Create the PostgreSQL database.
-poetry run .ci/scripts/postgres_exec.py "CREATE DATABASE synapse"
+psql -c "CREATE DATABASE synapse"
 
 echo "+++ Run synapse_port_db against test database"
 # TODO: this invocation of synapse_port_db (and others below) used to be prepended with `coverage run`,
@@ -45,9 +45,23 @@ rm .ci/test_db.db
 poetry run update_synapse_database --database-config .ci/sqlite-config.yaml --run-background-updates
 
 # re-create the PostgreSQL database.
-poetry run .ci/scripts/postgres_exec.py \
-  "DROP DATABASE synapse" \
-  "CREATE DATABASE synapse"
+psql \
+  -c "DROP DATABASE synapse" \
+  -c "CREATE DATABASE synapse"
 
 echo "+++ Run synapse_port_db against empty database"
 poetry run synapse_port_db --sqlite-database .ci/test_db.db --postgres-config .ci/postgres-config.yaml
+
+echo "--- Create a brand new postgres database from schema"
+cp .ci/postgres-config.yaml .ci/postgres-config-unported.yaml
+sed -i -e 's/database: synapse/database: synapse_unported/' .ci/postgres-config-unported.yaml
+psql -c "CREATE DATABASE synapse_unported"
+poetry run update_synapse_database --database-config .ci/postgres-config-unported.yaml --run-background-updates
+
+echo "+++ Comparing ported schema with unported schema"
+# Ignore the tables that portdb creates. (Should it tidy them up when the porting is completed?)
+psql synapse -c "DROP TABLE port_from_sqlite3;"
+pg_dump --format=plain --schema-only --no-tablespaces --no-acl --no-owner synapse_unported > unported.sql
+pg_dump --format=plain --schema-only --no-tablespaces --no-acl --no-owner synapse          >   ported.sql
+# By default, `diff` returns zero if there are no changes and nonzero otherwise
+diff -u unported.sql ported.sql | tee schema_diff
\ No newline at end of file
diff --git a/.dockerignore b/.dockerignore
index 7809863ef328..1c6905b1bbb3 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -4,8 +4,14 @@
 # things to include
 !docker
 !synapse
+!rust
 !README.rst
 !pyproject.toml
 !poetry.lock
+!Cargo.lock
+!build_rust.py
+
+rust/target
+synapse/*.so
 
 **/__pycache__
diff --git a/.github/workflows/latest_deps.yml b/.github/workflows/latest_deps.yml
index 7dac617c4bec..8366ac9393e3 100644
--- a/.github/workflows/latest_deps.yml
+++ b/.github/workflows/latest_deps.yml
@@ -5,7 +5,7 @@
 #
 # As an overview this workflow:
 # - checks out develop,
-# - installs from source, pulling in the dependencies like a fresh `pip install` would, and 
+# - installs from source, pulling in the dependencies like a fresh `pip install` would, and
 # - runs mypy and test suites in that checkout.
 #
 # Based on the twisted trunk CI job.
@@ -26,12 +26,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
       # The dev dependencies aren't exposed in the wheel metadata (at least with current
       # poetry-core versions), so we install with poetry.
       - uses: matrix-org/setup-python-poetry@v1
         with:
           python-version: "3.x"
-          poetry-version: "1.2.0b1"
+          poetry-version: "1.2.0"
           extras: "all"
       # Dump installed versions for debugging.
       - run: poetry run pip list > before.txt
@@ -53,6 +60,14 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
       - run: sudo apt-get -qq install xmlsec1
       - name: Set up PostgreSQL ${{ matrix.postgres-version }}
         if: ${{ matrix.postgres-version }}
@@ -69,6 +84,12 @@ jobs:
         if: ${{ matrix.postgres-version }}
         timeout-minutes: 2
         run: until pg_isready -h localhost; do sleep 1; done
+
+      # We nuke the local copy, as we've installed synapse into the virtualenv
+      # (rather than use an editable install, which we no longer support). If we
+      # don't do this then python can't find the native lib.
+      - run: rm -rf synapse/
+
       - run: python -m twisted.trial --jobs=2 tests
         env:
           SYNAPSE_POSTGRES: ${{ matrix.database == 'postgres' || '' }}
@@ -113,6 +134,14 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
       - name: Ensure sytest runs `pip install`
         # Delete the lockfile so sytest will `pip install` rather than `poetry install`
         run: rm /src/poetry.lock
@@ -187,4 +216,3 @@ jobs:
         with:
           update_existing: true
           filename: .ci/latest_deps_build_failed_issue_template.md
-
diff --git a/.github/workflows/release-artifacts.yml b/.github/workflows/release-artifacts.yml
index ed4fc6179db3..0708d631cd36 100644
--- a/.github/workflows/release-artifacts.yml
+++ b/.github/workflows/release-artifacts.yml
@@ -15,7 +15,7 @@ on:
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
-  
+
 permissions:
   contents: write
 
@@ -89,9 +89,67 @@ jobs:
           name: debs
           path: debs/*
 
+  build-wheels:
+    name: Build wheels on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-20.04, macos-10.15]
+        is_pr:
+          - ${{ startsWith(github.ref, 'refs/pull/') }}
+
+        exclude:
+          # Don't build macos wheels on PR CI.
+          - is_pr: true
+            os: "macos-10.15"
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: actions/setup-python@v3
+
+      - name: Install cibuildwheel
+        run: python -m pip install cibuildwheel==2.9.0 poetry==1.2.0
+
+      # Only build a single wheel in CI.
+      - name: Set env vars.
+        run: |
+          echo "CIBW_BUILD="cp37-manylinux_x86_64"" >> $GITHUB_ENV
+        if: startsWith(github.ref, 'refs/pull/')
+
+      - name: Build wheels
+        run: python -m cibuildwheel --output-dir wheelhouse
+        env:
+          # Skip testing for platforms which various libraries don't have wheels
+          # for, and so need extra build deps.
+          CIBW_TEST_SKIP: pp39-* *i686* *musl* pp37-macosx*
+
+      - uses: actions/upload-artifact@v3
+        with:
+          name: Wheel
+          path: ./wheelhouse/*.whl
+
   build-sdist:
-    name: "Build pypi distribution files"
-    uses: "matrix-org/backend-meta/.github/workflows/packaging.yml@v1"
+    name: Build sdist
+    runs-on: ubuntu-latest
+    if: ${{ !startsWith(github.ref, 'refs/pull/') }}
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: '3.10'
+
+      - run: pip install build
+
+      - name: Build sdist
+        run: python -m build --sdist
+
+      - uses: actions/upload-artifact@v2
+        with:
+          name: Sdist
+          path: dist/*.tar.gz
+
 
   # if it's a tag, create a release and attach the artifacts to it
   attach-assets:
@@ -99,6 +157,7 @@ jobs:
     if: ${{ !failure() && !cancelled() && startsWith(github.ref, 'refs/tags/') }}
     needs:
       - build-debs
+      - build-wheels
       - build-sdist
     runs-on: ubuntu-latest
     steps:
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index bc1de2893c1c..9fe61930a55a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -10,14 +10,33 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  # Job to detect what has changed so we don't run e.g. Rust checks on PRs that
+  # don't modify Rust code.
+  changes:
+    runs-on: ubuntu-latest
+    outputs:
+      rust: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.rust }}
+    steps:
+    - uses: dorny/paths-filter@v2
+      id: filter
+      # We only check on PRs
+      if: startsWith(github.ref, 'refs/pull/')
+      with:
+        filters: |
+          rust:
+            - 'rust/**'
+            - 'Cargo.toml'
+
   check-sampleconfig:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-python@v2
-      - run: pip install .
-      - run: scripts-dev/generate_sample_config.sh --check
-      - run: scripts-dev/config-lint.sh
+      - uses: matrix-org/setup-python-poetry@v1
+        with:
+          extras: "all"
+      - run: poetry run scripts-dev/generate_sample_config.sh --check
+      - run: poetry run scripts-dev/config-lint.sh
 
   check-schema-delta:
     runs-on: ubuntu-latest
@@ -59,16 +78,59 @@ jobs:
       - uses: actions/checkout@v2
         with:
           ref: ${{ github.event.pull_request.head.sha }}
-          fetch-depth: 0
       - uses: matrix-org/setup-python-poetry@v1
         with:
           extras: "all"
       - run: poetry run scripts-dev/check_pydantic_models.py
 
+  lint-clippy:
+    runs-on: ubuntu-latest
+    needs: changes
+    if: ${{ needs.changes.outputs.rust == 'true' }}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: 1.58.1
+            override: true
+            components: clippy
+      - uses: Swatinem/rust-cache@v2
+
+      - run: cargo clippy
+
+  lint-rustfmt:
+    runs-on: ubuntu-latest
+    needs: changes
+    if: ${{ needs.changes.outputs.rust == 'true' }}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: 1.58.1
+            override: true
+            components: rustfmt
+      - uses: Swatinem/rust-cache@v2
+
+      - run: cargo fmt --check
+
   # Dummy step to gate other tests on without repeating the whole list
   linting-done:
     if: ${{ !cancelled() }} # Run this even if prior jobs were skipped
-    needs: [lint, lint-crlf, lint-newsfile, lint-pydantic, check-sampleconfig, check-schema-delta]
+    needs:
+      - lint
+      - lint-crlf
+      - lint-newsfile
+      - lint-pydantic
+      - check-sampleconfig
+      - check-schema-delta
+      - lint-clippy
+      - lint-rustfmt
     runs-on: ubuntu-latest
     steps:
       - run: "true"
@@ -135,16 +197,54 @@ jobs:
     # Note: sqlite only; no postgres
     if: ${{ !cancelled() && !failure() }} # Allow previous steps to be skipped, but not fail
     needs: linting-done
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
-      - name: Test with old deps
-        uses: docker://ubuntu:focal # For old python and sqlite
-        # Note: focal seems to be using 3.8, but the oldest is 3.7?
-        # See https://github.com/matrix-org/synapse/issues/12343
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
         with:
-          workdir: /github/workspace
-          entrypoint: .ci/scripts/test_old_deps.sh
+            toolchain: 1.58.1
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
+      # There aren't wheels for some of the older deps, so we need to install
+      # their build dependencies
+      - run: |
+          sudo apt-get -qq install build-essential libffi-dev python-dev \
+          libxml2-dev libxslt-dev xmlsec1 zlib1g-dev libjpeg-dev libwebp-dev
+
+      - uses: actions/setup-python@v4
+        with:
+          python-version: '3.7'
+
+      # Calculating the old-deps actually takes a bunch of time, so we cache the
+      # pyproject.toml / poetry.lock. We need to cache pyproject.toml as
+      # otherwise the `poetry install` step will error due to the poetry.lock
+      # file being outdated.
+      #
+      # This caches the output of `Prepare old deps`, which should generate the
+      # same `pyproject.toml` and `poetry.lock` for a given `pyproject.toml` input.
+      - uses: actions/cache@v3
+        id: cache-poetry-old-deps
+        name: Cache poetry.lock
+        with:
+          path: |
+            poetry.lock
+            pyproject.toml
+          key: poetry-old-deps2-${{ hashFiles('pyproject.toml') }}
+      - name: Prepare old deps
+        if: steps.cache-poetry-old-deps.outputs.cache-hit != 'true'
+        run: .ci/scripts/prepare_old_deps.sh
+
+      # We only now install poetry so that `setup-python-poetry` caches the
+      # right poetry.lock's dependencies.
+      - uses: matrix-org/setup-python-poetry@v1
+        with:
+          python-version: '3.7'
+          extras: "all test"
+
+      - run: poetry run trial -j2 tests
       - name: Dump logs
         # Logs are most useful when the command fails, always include them.
         if: ${{ always() }}
@@ -216,6 +316,14 @@ jobs:
       - uses: actions/checkout@v2
       - name: Prepare test blacklist
         run: cat sytest-blacklist .ci/worker-blacklist > synapse-blacklist-with-workers
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: 1.58.1
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
       - name: Run SyTest
         run: /bootstrap.sh synapse
         working-directory: /src
@@ -254,18 +362,22 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
-      - run: sudo apt-get -qq install xmlsec1
+      - run: sudo apt-get -qq install xmlsec1 postgresql-client
       - uses: matrix-org/setup-python-poetry@v1
         with:
           extras: "postgres"
       - run: .ci/scripts/test_export_data_command.sh
+        env:
+          PGHOST: localhost
+          PGUSER: postgres
+          PGPASSWORD: postgres
+          PGDATABASE: postgres
+
 
   portdb:
     if: ${{ !failure() && !cancelled() }} # Allow previous steps to be skipped, but not fail
     needs: linting-done
     runs-on: ubuntu-latest
-    env:
-      TOP: ${{ github.workspace }}
     strategy:
       matrix:
         include:
@@ -291,12 +403,27 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
-      - run: sudo apt-get -qq install xmlsec1
+      - run: sudo apt-get -qq install xmlsec1 postgresql-client
       - uses: matrix-org/setup-python-poetry@v1
         with:
           python-version: ${{ matrix.python-version }}
           extras: "postgres"
       - run: .ci/scripts/test_synapse_port_db.sh
+        id: run_tester_script
+        env:
+          PGHOST: localhost
+          PGUSER: postgres
+          PGPASSWORD: postgres
+          PGDATABASE: postgres
+      - name: "Upload schema differences"
+        uses: actions/upload-artifact@v3
+        if: ${{ failure() && !cancelled() && steps.run_tester_script.outcome == 'failure' }}
+        with:
+          name: Schema dumps
+          path: |
+            unported.sql
+            ported.sql
+            schema_diff
 
   complement:
     if: "${{ !failure() && !cancelled() }}"
@@ -322,6 +449,13 @@ jobs:
         with:
           path: synapse
 
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: 1.58.1
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
       - name: Prepare Complement's Prerequisites
         run: synapse/.ci/scripts/setup_complement_prerequisites.sh
 
@@ -331,20 +465,36 @@ jobs:
         shell: bash
         name: Run Complement Tests
 
+  cargo-test:
+    if: ${{ needs.changes.outputs.rust == 'true' }}
+    runs-on: ubuntu-latest
+    needs:
+      - linting-done
+      - changes
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: 1.58.1
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
+      - run: cargo test
+
   # a job which marks all the other jobs as complete, thus allowing PRs to be merged.
   tests-done:
     if: ${{ always() }}
     needs:
-      - check-sampleconfig
-      - lint
-      - lint-crlf
-      - lint-newsfile
       - trial
       - trial-olddeps
       - sytest
       - export-data
       - portdb
       - complement
+      - cargo-test
     runs-on: ubuntu-latest
     steps:
       - uses: matrix-org/done-action@v2
@@ -352,5 +502,7 @@ jobs:
           needs: ${{ toJSON(needs) }}
 
           # The newsfile lint may be skipped on non PR builds
-          skippable:
+          # Cargo test is skipped if there is no changes on Rust code
+          skippable: |
             lint-newsfile
+            cargo-test
diff --git a/.github/workflows/twisted_trunk.yml b/.github/workflows/twisted_trunk.yml
index 0906101cc1c1..8fa2fbdea0e8 100644
--- a/.github/workflows/twisted_trunk.yml
+++ b/.github/workflows/twisted_trunk.yml
@@ -16,6 +16,14 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
       - uses: matrix-org/setup-python-poetry@v1
         with:
           python-version: "3.x"
@@ -34,6 +42,14 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - run: sudo apt-get -qq install xmlsec1
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
       - uses: matrix-org/setup-python-poetry@v1
         with:
           python-version: "3.x"
@@ -66,6 +82,14 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+      - uses: Swatinem/rust-cache@v2
+
       - name: Patch dependencies
         # Note: The poetry commands want to create a virtualenv in /src/.venv/,
         #       but the sytest-synapse container expects it to be in /venv/.
diff --git a/.gitignore b/.gitignore
index e58affb24125..15fbfdddf195 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,8 +15,9 @@ _trial_temp*/
 .DS_Store
 __pycache__/
 
-# We do want the poetry lockfile.
+# We do want the poetry and cargo lockfile.
 !poetry.lock
+!Cargo.lock
 
 # stuff that is likely to exist when you run a server locally
 /*.db
@@ -60,3 +61,10 @@ book/
 # complement
 /complement-*
 /master.tar.gz
+
+# rust
+/target/
+/synapse/*.so
+
+# Poetry will create a setup.py, which we don't want to include.
+/setup.py
diff --git a/CHANGES.md b/CHANGES.md
index be44903bfe83..fbb57f0e04e1 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,117 @@
+Synapse 1.68.0 (2022-09-27)
+===========================
+
+Please note that Synapse will now refuse to start if configured to use a version of SQLite older than 3.27.
+
+In addition, please note that installing Synapse from a source checkout now requires a recent Rust compiler.
+Those using packages will not be affected. On most platforms, installing with `pip install matrix-synapse` will not be affected.
+See the [upgrade notes](https://matrix-org.github.io/synapse/v1.68/upgrade.html#upgrading-to-v1680).
+
+Bugfixes
+--------
+
+- Fix packaging to include `Cargo.lock` in `sdist`. ([\#13909](https://github.com/matrix-org/synapse/issues/13909))
+
+
+Synapse 1.68.0rc2 (2022-09-23)
+==============================
+
+Bugfixes
+--------
+
+- Fix building from packaged sdist. Broken in v1.68.0rc1. ([\#13866](https://github.com/matrix-org/synapse/issues/13866))
+
+
+Internal Changes
+----------------
+
+- Fix the release script not publishing binary wheels. ([\#13850](https://github.com/matrix-org/synapse/issues/13850))
+- Lower minimum supported rustc version to 1.58.1. ([\#13857](https://github.com/matrix-org/synapse/issues/13857))
+- Lock Rust dependencies' versions. ([\#13858](https://github.com/matrix-org/synapse/issues/13858))
+
+
+Synapse 1.68.0rc1 (2022-09-20)
+==============================
+
+Features
+--------
+
+- Keep track of when we fail to process a pulled event over federation so we can intelligently back off in the future. ([\#13589](https://github.com/matrix-org/synapse/issues/13589), [\#13814](https://github.com/matrix-org/synapse/issues/13814))
+- Add an [admin API endpoint to fetch messages within a particular window of time](https://matrix-org.github.io/synapse/v1.68/admin_api/rooms.html#room-messages-api). ([\#13672](https://github.com/matrix-org/synapse/issues/13672))
+- Add an [admin API endpoint to find a user based on their external ID in an auth provider](https://matrix-org.github.io/synapse/v1.68/admin_api/user_admin_api.html#find-a-user-based-on-their-id-in-an-auth-provider). ([\#13810](https://github.com/matrix-org/synapse/issues/13810))
+- Cancel the processing of key query requests when they time out. ([\#13680](https://github.com/matrix-org/synapse/issues/13680))
+- Improve validation of request bodies for the following client-server API endpoints: [`/account/3pid/msisdn/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3pidmsisdnrequesttoken), [`/org.matrix.msc3720/account_status`](https://github.com/matrix-org/matrix-spec-proposals/blob/babolivier/user_status/proposals/3720-account-status.md#post-_matrixclientv1account_status), [`/account/3pid/add`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3pidadd), [`/account/3pid/bind`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3pidbind), [`/account/3pid/delete`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3piddelete) and [`/account/3pid/unbind`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3pidunbind). ([\#13687](https://github.com/matrix-org/synapse/issues/13687), [\#13736](https://github.com/matrix-org/synapse/issues/13736))
+- Document the timestamp when a user accepts the consent, if [consent tracking](https://matrix-org.github.io/synapse/latest/consent_tracking.html) is used. ([\#13741](https://github.com/matrix-org/synapse/issues/13741))
+- Add a `listeners[x].request_id_header` configuration option to specify which request header to extract and use as the request ID in order to correlate requests from a reverse proxy. ([\#13801](https://github.com/matrix-org/synapse/issues/13801))
+
+
+Bugfixes
+--------
+
+- Fix a bug introduced in Synapse 1.41.0 where the `/hierarchy` API returned non-standard information (a `room_id` field under each entry in `children_state`). ([\#13506](https://github.com/matrix-org/synapse/issues/13506))
+- Fix a long-standing bug where previously rejected events could end up in room state because they pass auth checks given the current state of the room. ([\#13723](https://github.com/matrix-org/synapse/issues/13723))
+- Fix a long-standing bug where Synapse fails to start if a signing key file contains an empty line. ([\#13738](https://github.com/matrix-org/synapse/issues/13738))
+- Fix a long-standing bug where Synapse would fail to handle malformed user IDs or room aliases gracefully in certain cases. ([\#13746](https://github.com/matrix-org/synapse/issues/13746))
+- Fix a long-standing bug where device lists would remain cached when remote users left and rejoined the last room shared with the local homeserver. ([\#13749](https://github.com/matrix-org/synapse/issues/13749), [\#13826](https://github.com/matrix-org/synapse/issues/13826))
+- Fix a long-standing bug that could cause stale caches in some rare cases on the first startup of Synapse with replication. ([\#13766](https://github.com/matrix-org/synapse/issues/13766))
+- Fix a long-standing spec compliance bug where Synapse would accept a trailing slash on the end of `/get_missing_events` federation requests. ([\#13789](https://github.com/matrix-org/synapse/issues/13789))
+- Delete associated data from `event_failed_pull_attempts`, `insertion_events`, `insertion_event_extremities`, `insertion_event_extremities`, `insertion_event_extremities` when purging the room. ([\#13825](https://github.com/matrix-org/synapse/issues/13825))
+
+
+Improved Documentation
+----------------------
+
+- Note that `libpq` is required on ARM-based Macs. ([\#13480](https://github.com/matrix-org/synapse/issues/13480))
+- Fix a mistake in the config manual introduced in Synapse 1.22.0: the `event_cache_size` _is_ scaled by `caches.global_factor`. ([\#13726](https://github.com/matrix-org/synapse/issues/13726))
+- Fix a typo in the documentation for the login ratelimiting configuration. ([\#13727](https://github.com/matrix-org/synapse/issues/13727))
+- Define Synapse's compatability policy for SQLite versions. ([\#13728](https://github.com/matrix-org/synapse/issues/13728))
+- Add docs for the common fix of deleting the `matrix_synapse.egg-info/` directory for fixing Python dependency problems. ([\#13785](https://github.com/matrix-org/synapse/issues/13785))
+- Update request log format documentation to mention the format used when the authenticated user is controlling another user. ([\#13794](https://github.com/matrix-org/synapse/issues/13794))
+
+
+Deprecations and Removals
+-------------------------
+
+- Synapse will now refuse to start if configured to use SQLite < 3.27. ([\#13760](https://github.com/matrix-org/synapse/issues/13760))
+- Don't include redundant `prev_state` in new events. Contributed by Denis Kariakin (@dakariakin). ([\#13791](https://github.com/matrix-org/synapse/issues/13791))
+
+
+Internal Changes
+----------------
+
+- Add a stub Rust crate. ([\#12595](https://github.com/matrix-org/synapse/issues/12595), [\#13734](https://github.com/matrix-org/synapse/issues/13734), [\#13735](https://github.com/matrix-org/synapse/issues/13735), [\#13743](https://github.com/matrix-org/synapse/issues/13743), [\#13763](https://github.com/matrix-org/synapse/issues/13763), [\#13769](https://github.com/matrix-org/synapse/issues/13769), [\#13778](https://github.com/matrix-org/synapse/issues/13778))
+- Bump the minimum dependency of `matrix_common` to 1.3.0 to make use of the `MXCUri` class. Use `MXCUri` to simplify media retention test code. ([\#13162](https://github.com/matrix-org/synapse/issues/13162))
+- Add and populate the `event_stream_ordering` column on the `receipts` table for future optimisation of push action processing. Contributed by Nick @ Beeper (@fizzadar). ([\#13703](https://github.com/matrix-org/synapse/issues/13703))
+- Rename the `EventFormatVersions` enum values so that they line up with room version numbers. ([\#13706](https://github.com/matrix-org/synapse/issues/13706))
+- Update trial old deps CI to use Poetry 1.2.0. ([\#13707](https://github.com/matrix-org/synapse/issues/13707), [\#13725](https://github.com/matrix-org/synapse/issues/13725))
+- Add experimental configuration option to allow disabling legacy Prometheus metric names. ([\#13714](https://github.com/matrix-org/synapse/issues/13714), [\#13717](https://github.com/matrix-org/synapse/issues/13717), [\#13718](https://github.com/matrix-org/synapse/issues/13718))
+- Fix typechecking with latest types-jsonschema. ([\#13724](https://github.com/matrix-org/synapse/issues/13724))
+- Strip number suffix from instance name to consolidate services that traces are spread over. ([\#13729](https://github.com/matrix-org/synapse/issues/13729))
+- Instrument `get_metadata_for_events` for understandable traces in Jaeger. ([\#13730](https://github.com/matrix-org/synapse/issues/13730))
+- Remove old queries to join room memberships to current state events. Contributed by Nick @ Beeper (@fizzadar). ([\#13745](https://github.com/matrix-org/synapse/issues/13745))
+- Avoid raising an error due to malformed user IDs in `get_current_hosts_in_room`. Malformed user IDs cannot currently join a room, so this error would not be hit. ([\#13748](https://github.com/matrix-org/synapse/issues/13748))
+- Update the docstrings for `get_users_in_room` and `get_current_hosts_in_room` to explain the impact of partial state. ([\#13750](https://github.com/matrix-org/synapse/issues/13750))
+- Use an additional database query when persisting receipts. ([\#13752](https://github.com/matrix-org/synapse/issues/13752))
+- Preparatory work for storing thread IDs for notifications and receipts. ([\#13753](https://github.com/matrix-org/synapse/issues/13753))
+- Re-type hint some collections as read-only. ([\#13754](https://github.com/matrix-org/synapse/issues/13754))
+- Remove unused Prometheus recording rules from `synapse-v2.rules` and add comments describing where the rest are used. ([\#13756](https://github.com/matrix-org/synapse/issues/13756))
+- Add a check for editable installs if the Rust library needs rebuilding. ([\#13759](https://github.com/matrix-org/synapse/issues/13759))
+- Tag traces with the instance name to be able to easily jump into the right logs and filter traces by instance. ([\#13761](https://github.com/matrix-org/synapse/issues/13761))
+- Concurrently fetch room push actions when calculating badge counts. Contributed by Nick @ Beeper (@fizzadar). ([\#13765](https://github.com/matrix-org/synapse/issues/13765))
+- Update the script which makes full schema dumps. ([\#13770](https://github.com/matrix-org/synapse/issues/13770))
+- Deduplicate `is_server_notices_room`. ([\#13780](https://github.com/matrix-org/synapse/issues/13780))
+- Simplify the dependency DAG in the tests workflow. ([\#13784](https://github.com/matrix-org/synapse/issues/13784))
+- Remove an old, incorrect migration file. ([\#13788](https://github.com/matrix-org/synapse/issues/13788))
+- Remove unused method in `synapse.api.auth.Auth`. ([\#13795](https://github.com/matrix-org/synapse/issues/13795))
+- Fix a memory leak when running the unit tests. ([\#13798](https://github.com/matrix-org/synapse/issues/13798))
+- Use partial indices on SQLite. ([\#13802](https://github.com/matrix-org/synapse/issues/13802))
+- Check that portdb generates the same postgres schema as that in the source tree. ([\#13808](https://github.com/matrix-org/synapse/issues/13808))
+- Fix Docker build when Rust .so has been built locally first. ([\#13811](https://github.com/matrix-org/synapse/issues/13811))
+- Complement: Initialise the Postgres database directly inside the target image instead of the base Postgres image to fix building using Buildah. ([\#13819](https://github.com/matrix-org/synapse/issues/13819))
+- Support providing an index predicate clause when doing upserts. ([\#13822](https://github.com/matrix-org/synapse/issues/13822))
+- Minor speedups to linting in CI. ([\#13827](https://github.com/matrix-org/synapse/issues/13827))
+
+
 Synapse 1.67.0 (2022-09-13)
 ===========================
 
@@ -46,7 +160,7 @@ Bugfixes
 - Fix [MSC3030](https://github.com/matrix-org/matrix-spec-proposals/pull/3030) `/timestamp_to_event` endpoint to return the correct next event when the events have the same timestamp. ([\#13658](https://github.com/matrix-org/synapse/issues/13658))
 - Fix bug where we wedge media plugins if clients disconnect early. Introduced in v1.22.0. ([\#13660](https://github.com/matrix-org/synapse/issues/13660))
 - Fix a long-standing bug which meant that keys for unwhitelisted servers were not returned by `/_matrix/key/v2/query`. ([\#13683](https://github.com/matrix-org/synapse/issues/13683))
-- Fix a bug introduced in Synapse v1.20.0 that would cause the unstable unread counts from [MSC2654](https://github.com/matrix-org/matrix-spec-proposals/pull/2654) to be calculated even if the feature is disabled. ([\#13694](https://github.com/matrix-org/synapse/issues/13694))
+- Fix a bug introduced in Synapse 1.20.0 that would cause the unstable unread counts from [MSC2654](https://github.com/matrix-org/matrix-spec-proposals/pull/2654) to be calculated even if the feature is disabled. ([\#13694](https://github.com/matrix-org/synapse/issues/13694))
 
 
 Updates to the Docker image
@@ -73,7 +187,7 @@ Deprecations and Removals
 
 - Drop support for calling `/_matrix/client/v3/rooms/{roomId}/invite` without an `id_access_token`, which was not permitted by the spec. Contributed by @Vetchu. ([\#13241](https://github.com/matrix-org/synapse/issues/13241))
 - Remove redundant `_get_joined_users_from_context` cache. Contributed by Nick @ Beeper (@fizzadar). ([\#13569](https://github.com/matrix-org/synapse/issues/13569))
-- Remove the ability to use direct TCP replication with workers. Direct TCP replication was deprecated in Synapse v1.18.0. Workers now require using Redis. ([\#13647](https://github.com/matrix-org/synapse/issues/13647))
+- Remove the ability to use direct TCP replication with workers. Direct TCP replication was deprecated in Synapse 1.18.0. Workers now require using Redis. ([\#13647](https://github.com/matrix-org/synapse/issues/13647))
 - Remove support for unstable [private read receipts](https://github.com/matrix-org/matrix-spec-proposals/pull/2285). ([\#13653](https://github.com/matrix-org/synapse/issues/13653), [\#13692](https://github.com/matrix-org/synapse/issues/13692))
 
 
@@ -117,7 +231,7 @@ was originally planned for Synapse 1.64, but was later deferred until now. See
 the [upgrade notes](https://matrix-org.github.io/synapse/v1.66/upgrade.html#upgrading-to-v1660) for more details.
 
 Deployments with multiple workers should note that the direct TCP replication
-configuration was deprecated in Synapse v1.18.0 and will be removed in Synapse
+configuration was deprecated in Synapse 1.18.0 and will be removed in Synapse
 v1.67.0. In particular, the TCP `replication` [listener](https://matrix-org.github.io/synapse/v1.66/usage/configuration/config_documentation.html#listeners)
 type (not to be confused with the `replication` resource on the `http` listener
 type) and the `worker_replication_port` config option will be removed .
@@ -247,7 +361,7 @@ Bugfixes
 --------
 
 - Update the version of the LDAP3 auth provider module included in the `matrixdotorg/synapse` DockerHub images and the Debian packages hosted on packages.matrix.org to 0.2.2. This version fixes a regression in the module. ([\#13470](https://github.com/matrix-org/synapse/issues/13470))
-- Fix a bug introduced in Synapse v1.41.0 where the `/hierarchy` API returned non-standard information (a `room_id` field under each entry in `children_state`) (this was reverted in v1.65.0rc2, see changelog notes above). ([\#13365](https://github.com/matrix-org/synapse/issues/13365))
+- Fix a bug introduced in Synapse 1.41.0 where the `/hierarchy` API returned non-standard information (a `room_id` field under each entry in `children_state`) (this was reverted in v1.65.0rc2, see changelog notes above). ([\#13365](https://github.com/matrix-org/synapse/issues/13365))
 - Fix a bug introduced in Synapse 0.24.0 that would respond with the wrong error status code to `/joined_members` requests when the requester is not a current member of the room. Contributed by @andrewdoh. ([\#13374](https://github.com/matrix-org/synapse/issues/13374))
 - Fix bug in handling of typing events for appservices. Contributed by Nick @ Beeper (@fizzadar). ([\#13392](https://github.com/matrix-org/synapse/issues/13392))
 - Fix a bug introduced in Synapse 1.57.0 where rooms listed in `exclude_rooms_from_sync` in the configuration file would not be properly excluded from incremental syncs. ([\#13408](https://github.com/matrix-org/synapse/issues/13408))
@@ -312,7 +426,7 @@ No significant changes since 1.64.0rc2.
 Deprecation Warning
 -------------------
 
-Synapse v1.66.0 will remove the ability to delegate the tasks of verifying email address ownership, and password reset confirmation, to an identity server.
+Synapse 1.66.0 will remove the ability to delegate the tasks of verifying email address ownership, and password reset confirmation, to an identity server.
 
 If you require your homeserver to verify e-mail addresses or to support password resets via e-mail, please configure your homeserver with SMTP access so that it can send e-mails on its own behalf.
 [Consult the configuration documentation for more information.](https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#email)
@@ -321,7 +435,7 @@ If you require your homeserver to verify e-mail addresses or to support password
 Synapse 1.64.0rc2 (2022-07-29)
 ==============================
 
-This RC reintroduces support for `account_threepid_delegates.email`, which was removed in 1.64.0rc1. It remains deprecated and will be removed altogether in Synapse v1.66.0. ([\#13406](https://github.com/matrix-org/synapse/issues/13406))
+This RC reintroduces support for `account_threepid_delegates.email`, which was removed in 1.64.0rc1. It remains deprecated and will be removed altogether in Synapse 1.66.0. ([\#13406](https://github.com/matrix-org/synapse/issues/13406))
 
 
 Synapse 1.64.0rc1 (2022-07-26)
@@ -570,7 +684,7 @@ Bugfixes
 - Fix a bug introduced in Synapse 1.58 where Synapse would not report full version information when installed from a git checkout. This is a best-effort affair and not guaranteed to be stable. ([\#12973](https://github.com/matrix-org/synapse/issues/12973))
 - Fix a bug introduced in Synapse 1.60 where Synapse would fail to start if the `sqlite3` module was not available. ([\#12979](https://github.com/matrix-org/synapse/issues/12979))
 - Fix a bug where non-standard information was required when requesting the `/hierarchy` API over federation. Introduced
-  in Synapse v1.41.0. ([\#12991](https://github.com/matrix-org/synapse/issues/12991))
+  in Synapse 1.41.0. ([\#12991](https://github.com/matrix-org/synapse/issues/12991))
 - Fix a long-standing bug which meant that rate limiting was not restrictive enough in some cases. ([\#13018](https://github.com/matrix-org/synapse/issues/13018))
 - Fix a bug introduced in Synapse 1.58 where profile requests for a malformed user ID would ccause an internal error. Synapse now returns 400 Bad Request in this situation. ([\#13041](https://github.com/matrix-org/synapse/issues/13041))
 - Fix some inconsistencies in the event authentication code. ([\#13087](https://github.com/matrix-org/synapse/issues/13087), [\#13088](https://github.com/matrix-org/synapse/issues/13088))
@@ -1163,7 +1277,7 @@ If you have already upgraded to Synapse 1.57.0 without problem, then you have no
 Updates to the Docker image
 ---------------------------
 
-- Include version 0.2.0 of the Synapse LDAP Auth Provider module in the Docker image. This matches the version that was present in the Docker image for Synapse v1.56.0. ([\#12512](https://github.com/matrix-org/synapse/issues/12512))
+- Include version 0.2.0 of the Synapse LDAP Auth Provider module in the Docker image. This matches the version that was present in the Docker image for Synapse 1.56.0. ([\#12512](https://github.com/matrix-org/synapse/issues/12512))
 
 
 Synapse 1.57.0 (2022-04-19)
@@ -1415,10 +1529,10 @@ Features
 Bugfixes
 --------
 
-- Use the proper serialization format for bundled thread aggregations. The bug has existed since Synapse v1.48.0. ([\#12090](https://github.com/matrix-org/synapse/issues/12090))
+- Use the proper serialization format for bundled thread aggregations. The bug has existed since Synapse 1.48.0. ([\#12090](https://github.com/matrix-org/synapse/issues/12090))
 - Fix a long-standing bug when redacting events with relations. ([\#12113](https://github.com/matrix-org/synapse/issues/12113), [\#12121](https://github.com/matrix-org/synapse/issues/12121), [\#12130](https://github.com/matrix-org/synapse/issues/12130), [\#12189](https://github.com/matrix-org/synapse/issues/12189))
 - Fix a bug introduced in Synapse 1.7.2 whereby background updates are never run with the default background batch size. ([\#12157](https://github.com/matrix-org/synapse/issues/12157))
-- Fix a bug where non-standard information was returned from the `/hierarchy` API. Introduced in Synapse v1.41.0. ([\#12175](https://github.com/matrix-org/synapse/issues/12175))
+- Fix a bug where non-standard information was returned from the `/hierarchy` API. Introduced in Synapse 1.41.0. ([\#12175](https://github.com/matrix-org/synapse/issues/12175))
 - Fix a bug introduced in Synapse 1.54.0 that broke background updates on sqlite homeservers while search was disabled. ([\#12215](https://github.com/matrix-org/synapse/issues/12215))
 - Fix a long-standing bug when a `filter` argument with `event_fields` which did not include the `unsigned` field could result in a 500 error on `/sync`. ([\#12234](https://github.com/matrix-org/synapse/issues/12234))
 
@@ -1803,15 +1917,15 @@ Bugfixes
 - Fix a long-standing issue which could cause Synapse to incorrectly accept data in the unsigned field of events
   received over federation. ([\#11530](https://github.com/matrix-org/synapse/issues/11530))
 - Fix a long-standing bug where Synapse wouldn't cache a response indicating that a remote user has no devices. ([\#11587](https://github.com/matrix-org/synapse/issues/11587))
-- Fix an error that occurs whilst trying to get the federation status of a destination server that was working normally. This admin API was newly introduced in Synapse v1.49.0. ([\#11593](https://github.com/matrix-org/synapse/issues/11593))
+- Fix an error that occurs whilst trying to get the federation status of a destination server that was working normally. This admin API was newly introduced in Synapse 1.49.0. ([\#11593](https://github.com/matrix-org/synapse/issues/11593))
 - Fix bundled aggregations not being included in the `/sync` response, per [MSC2675](https://github.com/matrix-org/matrix-doc/pull/2675). ([\#11612](https://github.com/matrix-org/synapse/issues/11612), [\#11659](https://github.com/matrix-org/synapse/issues/11659), [\#11791](https://github.com/matrix-org/synapse/issues/11791))
 - Fix the `/_matrix/client/v1/room/{roomId}/hierarchy` endpoint returning incorrect fields which have been present since Synapse 1.49.0. ([\#11667](https://github.com/matrix-org/synapse/issues/11667))
 - Fix preview of some GIF URLs (like tenor.com). Contributed by Philippe Daouadi. ([\#11669](https://github.com/matrix-org/synapse/issues/11669))
-- Fix a bug where only the first 50 rooms from a space were returned from the `/hierarchy` API. This has existed since the introduction of the API in Synapse v1.41.0. ([\#11695](https://github.com/matrix-org/synapse/issues/11695))
-- Fix a bug introduced in Synapse v1.18.0 where password reset and address validation emails would not be sent if their subject was configured to use the 'app' template variable. Contributed by @br4nnigan. ([\#11710](https://github.com/matrix-org/synapse/issues/11710), [\#11745](https://github.com/matrix-org/synapse/issues/11745))
+- Fix a bug where only the first 50 rooms from a space were returned from the `/hierarchy` API. This has existed since the introduction of the API in Synapse 1.41.0. ([\#11695](https://github.com/matrix-org/synapse/issues/11695))
+- Fix a bug introduced in Synapse 1.18.0 where password reset and address validation emails would not be sent if their subject was configured to use the 'app' template variable. Contributed by @br4nnigan. ([\#11710](https://github.com/matrix-org/synapse/issues/11710), [\#11745](https://github.com/matrix-org/synapse/issues/11745))
 - Make the 'List Rooms' Admin API sort stable. Contributed by Daniël Sonck. ([\#11737](https://github.com/matrix-org/synapse/issues/11737))
 - Fix a long-standing bug where space hierarchy over federation would only work correctly some of the time. ([\#11775](https://github.com/matrix-org/synapse/issues/11775))
-- Fix a bug introduced in Synapse v1.46.0 that prevented `on_logged_out` module callbacks from being correctly awaited by Synapse. ([\#11786](https://github.com/matrix-org/synapse/issues/11786))
+- Fix a bug introduced in Synapse 1.46.0 that prevented `on_logged_out` module callbacks from being correctly awaited by Synapse. ([\#11786](https://github.com/matrix-org/synapse/issues/11786))
 
 
 Improved Documentation
@@ -1891,8 +2005,8 @@ This release candidate fixes a federation-breaking regression introduced in Syna
 Bugfixes
 --------
 
-- Fix a bug introduced in Synapse v1.0.0 whereby some device list updates would not be sent to remote homeservers if there were too many to send at once. ([\#11729](https://github.com/matrix-org/synapse/issues/11729))
-- Fix a bug introduced in Synapse v1.50.0rc1 whereby outbound federation could fail because too many EDUs were produced for device updates. ([\#11730](https://github.com/matrix-org/synapse/issues/11730))
+- Fix a bug introduced in Synapse 1.0.0 whereby some device list updates would not be sent to remote homeservers if there were too many to send at once. ([\#11729](https://github.com/matrix-org/synapse/issues/11729))
+- Fix a bug introduced in Synapse 1.50.0rc1 whereby outbound federation could fail because too many EDUs were produced for device updates. ([\#11730](https://github.com/matrix-org/synapse/issues/11730))
 
 
 Improved Documentation
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 000000000000..3ae36161b3cc
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,324 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
+[[package]]
+name = "blake2"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9cf849ee05b2ee5fba5e36f97ff8ec2533916700fc0758d40d92136a42f3388"
+dependencies = [
+ "digest",
+]
+
+[[package]]
+name = "block-buffer"
+version = "0.10.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "69cce20737498f97b993470a6e536b8523f0af7892a4f928cceb1ac5e52ebe7e"
+dependencies = [
+ "generic-array",
+]
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "crypto-common"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
+[[package]]
+name = "digest"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "adfbc57365a37acbd2ebf2b64d7e69bb766e2fea813521ed536f5d0520dcf86c"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+ "subtle",
+]
+
+[[package]]
+name = "generic-array"
+version = "0.14.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bff49e947297f3312447abdca79f45f4738097cc82b06e72054d2223f601f1b9"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
+[[package]]
+name = "hex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
+
+[[package]]
+name = "indoc"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "adab1eaa3408fb7f0c777a73e7465fd5656136fc93b670eb6df3c88c2c1344e3"
+
+[[package]]
+name = "libc"
+version = "0.2.132"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8371e4e5341c3a96db127eb2465ac681ced4c433e01dd0e938adbef26ba93ba5"
+
+[[package]]
+name = "lock_api"
+version = "0.4.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "327fa5b6a6940e4699ec49a9beae1ea4845c6bab9314e4f84ac68742139d8c53"
+dependencies = [
+ "autocfg",
+ "scopeguard",
+]
+
+[[package]]
+name = "once_cell"
+version = "1.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "074864da206b4973b84eb91683020dbefd6a8c3f0f38e054d93954e891935e4e"
+
+[[package]]
+name = "parking_lot"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3742b2c103b9f06bc9fff0a37ff4912935851bee6d36f3c02bcc755bcfec228f"
+dependencies = [
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09a279cbf25cb0757810394fbc1e359949b59e348145c643a939a525692e6929"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "redox_syscall",
+ "smallvec",
+ "windows-sys",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0a2ca2c61bc9f3d74d2886294ab7b9853abd9c1ad903a3ac7815c58989bb7bab"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "pyo3"
+version = "0.16.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0220c44442c9b239dd4357aa856ac468a4f5e1f0df19ddb89b2522952eb4c6ca"
+dependencies = [
+ "cfg-if",
+ "indoc",
+ "libc",
+ "parking_lot",
+ "pyo3-build-config",
+ "pyo3-ffi",
+ "pyo3-macros",
+ "unindent",
+]
+
+[[package]]
+name = "pyo3-build-config"
+version = "0.16.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c819d397859445928609d0ec5afc2da5204e0d0f73d6bf9e153b04e83c9cdc2"
+dependencies = [
+ "once_cell",
+ "target-lexicon",
+]
+
+[[package]]
+name = "pyo3-ffi"
+version = "0.16.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca882703ab55f54702d7bfe1189b41b0af10272389f04cae38fe4cd56c65f75f"
+dependencies = [
+ "libc",
+ "pyo3-build-config",
+]
+
+[[package]]
+name = "pyo3-macros"
+version = "0.16.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "568749402955ad7be7bad9a09b8593851cd36e549ac90bfd44079cea500f3f21"
+dependencies = [
+ "proc-macro2",
+ "pyo3-macros-backend",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "pyo3-macros-backend"
+version = "0.16.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "611f64e82d98f447787e82b8e7b0ebc681e1eb78fc1252668b2c605ffb4e1eb8"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbe448f377a7d6961e30f5955f9b8d106c3f5e449d493ee1b125c1d43c2b5179"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "redox_syscall"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb5a58c1855b4b6819d59012155603f0b22ad30cad752600aadfcb695265519a"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
+[[package]]
+name = "smallvec"
+version = "1.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fd0db749597d91ff862fd1d55ea87f7855a744a8425a64695b6fca237d1dad1"
+
+[[package]]
+name = "subtle"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6bdef32e8150c2a081110b42772ffe7d7c9032b606bc226c8260fd97e0976601"
+
+[[package]]
+name = "syn"
+version = "1.0.99"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "58dbef6ec655055e20b86b15a8cc6d439cca19b667537ac6a1369572d151ab13"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "synapse"
+version = "0.1.0"
+dependencies = [
+ "blake2",
+ "hex",
+ "pyo3",
+]
+
+[[package]]
+name = "target-lexicon"
+version = "0.12.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c02424087780c9b71cc96799eaeddff35af2bc513278cda5c99fc1f5d026d3c1"
+
+[[package]]
+name = "typenum"
+version = "1.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dcf81ac59edc17cc8697ff311e8f5ef2d99fcbd9817b34cec66f90b6c3dfd987"
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4f5b37a154999a8f3f98cc23a628d850e154479cd94decf3414696e12e31aaf"
+
+[[package]]
+name = "unindent"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "58ee9362deb4a96cef4d437d1ad49cffc9b9e92d202b6995674e928ce684f112"
+
+[[package]]
+name = "version_check"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
+
+[[package]]
+name = "windows-sys"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea04155a16a59f9eab786fe12a4a450e75cdb175f9e0d80da1e17db09f55b8d2"
+dependencies = [
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9bb8c3fd39ade2d67e9874ac4f3db21f0d710bee00fe7cab16949ec184eeaa47"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "180e6ccf01daf4c426b846dfc66db1fc518f074baa793aa7d9b9aaeffad6a3b6"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2e7917148b2812d1eeafaeb22a97e4813dfa60a3f8f78ebe204bcc88f12f024"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4dcd171b8776c41b97521e5da127a2d86ad280114807d0b2ab1e462bc764d9e1"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.36.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c811ca4a8c853ef420abd8592ba53ddbbac90410fab6903b3e79972a631f7680"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 000000000000..de141bdee9d3
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,5 @@
+# We make the whole Synapse folder a workspace so that we can run `cargo`
+# commands from the root (rather than having to cd into rust/).
+
+[workspace]
+members = ["rust"]
diff --git a/build_rust.py b/build_rust.py
new file mode 100644
index 000000000000..5c5e557ee847
--- /dev/null
+++ b/build_rust.py
@@ -0,0 +1,20 @@
+# A build script for poetry that adds the rust extension.
+
+import os
+from typing import Any, Dict
+
+from setuptools_rust import Binding, RustExtension
+
+
+def build(setup_kwargs: Dict[str, Any]) -> None:
+    original_project_dir = os.path.dirname(os.path.realpath(__file__))
+    cargo_toml_path = os.path.join(original_project_dir, "rust", "Cargo.toml")
+
+    extension = RustExtension(
+        target="synapse.synapse_rust",
+        path=cargo_toml_path,
+        binding=Binding.PyO3,
+        py_limited_api=True,
+    )
+    setup_kwargs.setdefault("rust_extensions", []).append(extension)
+    setup_kwargs["zip_safe"] = False
diff --git a/contrib/grafana/synapse.json b/contrib/grafana/synapse.json
index 248cd6d9ad5c..58061e2fced8 100644
--- a/contrib/grafana/synapse.json
+++ b/contrib/grafana/synapse.json
@@ -335,7 +335,7 @@
           "datasource": {
             "uid": "$datasource"
           },
-          "expr": "sum(rate(synapse_storage_events_persisted_events{instance=\"$instance\"}[$bucket_size]))",
+          "expr": "sum(rate(synapse_storage_events_persisted_events_total{instance=\"$instance\"}[$bucket_size]))",
           "hide": false,
           "instant": false,
           "legendFormat": "Events",
@@ -1423,7 +1423,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_background_process_ru_utime_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])+rate(synapse_background_process_ru_stime_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_background_process_ru_utime_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])+rate(synapse_background_process_ru_stime_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "hide": false,
               "instant": false,
@@ -1804,7 +1804,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_storage_events_persisted_events{instance=\"$instance\"}[$bucket_size])) without (job,index)",
+              "expr": "sum(rate(synapse_storage_events_persisted_events_total{instance=\"$instance\"}[$bucket_size])) without (job,index)",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -2437,7 +2437,7 @@
                 "uid": "$datasource"
               },
               "exemplar": false,
-              "expr": "sum(rate(synapse_state_res_db_for_biggest_room_seconds{instance=\"$instance\"}[1m]))",
+              "expr": "sum(rate(synapse_state_res_db_for_biggest_room_seconds_total{instance=\"$instance\"}[1m]))",
               "format": "time_series",
               "hide": false,
               "instant": false,
@@ -2451,7 +2451,7 @@
                 "uid": "$datasource"
               },
               "exemplar": false,
-              "expr": "sum(rate(synapse_state_res_cpu_for_biggest_room_seconds{instance=\"$instance\"}[1m]))",
+              "expr": "sum(rate(synapse_state_res_cpu_for_biggest_room_seconds_total{instance=\"$instance\"}[1m]))",
               "format": "time_series",
               "hide": false,
               "instant": false,
@@ -3425,7 +3425,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_background_process_ru_utime_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])+rate(synapse_background_process_ru_stime_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_background_process_ru_utime_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])+rate(synapse_background_process_ru_stime_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 1,
@@ -3518,7 +3518,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_background_process_db_txn_duration_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) +  rate(synapse_background_process_db_sched_duration_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_background_process_db_txn_duration_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) +  rate(synapse_background_process_db_sched_duration_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "hide": false,
               "intervalFactor": 1,
@@ -3726,7 +3726,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_federation_client_sent_transactions{instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_federation_client_sent_transactions_total{instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "successful txn rate",
@@ -3736,7 +3736,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_util_metrics_block_count{block_name=\"_send_new_transaction\",instance=\"$instance\"}[$bucket_size]) - ignoring (block_name) rate(synapse_federation_client_sent_transactions{instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_util_metrics_block_count_total{block_name=\"_send_new_transaction\",instance=\"$instance\"}[$bucket_size]) - ignoring (block_name) rate(synapse_federation_client_sent_transactions_total{instance=\"$instance\"}[$bucket_size]))",
               "legendFormat": "failed txn rate",
               "refId": "B"
             }
@@ -3826,7 +3826,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_federation_server_received_pdus{instance=~\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_federation_server_received_pdus_total{instance=~\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "pdus",
@@ -3836,7 +3836,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_federation_server_received_edus{instance=~\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_federation_server_received_edus_total{instance=~\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "edus",
@@ -3928,7 +3928,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_federation_client_sent_pdu_destinations:total{instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_federation_client_sent_pdu_destinations:total_total{instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 1,
@@ -3939,7 +3939,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_federation_client_sent_edus{instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_federation_client_sent_edus_total{instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "edus",
@@ -5042,7 +5042,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_http_httppusher_http_pushes_processed{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) and on (instance, job, index) (synapse_http_httppusher_http_pushes_failed + synapse_http_httppusher_http_pushes_processed) > 0",
+              "expr": "rate(synapse_http_httppusher_http_pushes_processed_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) and on (instance, job, index) (synapse_http_httppusher_http_pushes_failed_total + synapse_http_httppusher_http_pushes_processed_total) > 0",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -5054,7 +5054,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_http_httppusher_http_pushes_failed{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) and on (instance, job, index) (synapse_http_httppusher_http_pushes_failed + synapse_http_httppusher_http_pushes_processed) > 0",
+              "expr": "rate(synapse_http_httppusher_http_pushes_failed_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) and on (instance, job, index) (synapse_http_httppusher_http_pushes_failed_total + synapse_http_httppusher_http_pushes_processed_total) > 0",
               "format": "time_series",
               "intervalFactor": 2,
               "legendFormat": "failed {{job}}",
@@ -5268,12 +5268,12 @@
                 "uid": "${DS_PROMETHEUS}"
               },
               "exemplar": true,
-              "expr": "sum(rate(synapse_push_bulk_push_rule_evaluator_push_rules_state_size_counter{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_push_bulk_push_rule_evaluator_push_rules_state_size_counter_total{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
               "legendFormat": "{{index}}",
-              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_state_size_counter",
+              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_state_size_counter_total",
               "refId": "A",
               "step": 2
             }
@@ -5369,12 +5369,12 @@
                 "uid": "$datasource"
               },
               "exemplar": true,
-              "expr": "sum(rate(synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter_total{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
               "legendFormat": "{{index}}",
-              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter",
+              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter_total",
               "refId": "A",
               "step": 2
             }
@@ -5475,12 +5475,12 @@
                 "uid": "${DS_PROMETHEUS}"
               },
               "exemplar": true,
-              "expr": "sum(rate(synapse_util_caches_cache:hits{job=\"$job\",index=~\"$index\",name=\"push_rules_delta_state_cache_metric\",instance=\"$instance\"}[$bucket_size]))/sum(rate(synapse_util_caches_cache:total{job=\"$job\",index=~\"$index\", name=\"push_rules_delta_state_cache_metric\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_util_caches_cache_hits{job=\"$job\",index=~\"$index\",name=\"push_rules_delta_state_cache_metric\",instance=\"$instance\"}[$bucket_size]))/sum(rate(synapse_util_caches_cache{job=\"$job\",index=~\"$index\", name=\"push_rules_delta_state_cache_metric\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
               "legendFormat": "Hit Rate",
-              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter",
+              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter_total",
               "refId": "A",
               "step": 2
             },
@@ -5490,7 +5490,7 @@
                 "uid": "${DS_PROMETHEUS}"
               },
               "exemplar": true,
-              "expr": "sum(rate(synapse_util_caches_cache:total{job=\"$job\",index=~\"$index\", name=\"push_rules_delta_state_cache_metric\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_util_caches_cache{job=\"$job\",index=~\"$index\", name=\"push_rules_delta_state_cache_metric\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -5598,12 +5598,12 @@
                 "uid": "${DS_PROMETHEUS}"
               },
               "exemplar": true,
-              "expr": "sum(rate(synapse_util_caches_cache:hits{job=\"$job\",index=~\"$index\",name=\"room_push_rule_cache\",instance=\"$instance\"}[$bucket_size]))/sum(rate(synapse_util_caches_cache:total{job=\"$job\",index=~\"$index\", name=\"room_push_rule_cache\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_util_caches_cache_hits{job=\"$job\",index=~\"$index\",name=\"room_push_rule_cache\",instance=\"$instance\"}[$bucket_size]))/sum(rate(synapse_util_caches_cache{job=\"$job\",index=~\"$index\", name=\"room_push_rule_cache\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
               "legendFormat": "Hit Rate",
-              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter",
+              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter_total",
               "refId": "A",
               "step": 2
             },
@@ -5613,7 +5613,7 @@
                 "uid": "${DS_PROMETHEUS}"
               },
               "exemplar": true,
-              "expr": "sum(rate(synapse_util_caches_cache:total{job=\"$job\",index=~\"$index\", name=\"room_push_rule_cache\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_util_caches_cache{job=\"$job\",index=~\"$index\", name=\"room_push_rule_cache\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -5719,12 +5719,12 @@
                 "uid": "${DS_PROMETHEUS}"
               },
               "exemplar": true,
-              "expr": "sum(rate(synapse_util_caches_cache:hits{job=\"$job\",index=~\"$index\",name=\"_get_rules_for_room\",instance=\"$instance\"}[$bucket_size]))/sum(rate(synapse_util_caches_cache:total{job=\"$job\",index=~\"$index\", name=\"_get_rules_for_room\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_util_caches_cache_hits{job=\"$job\",index=~\"$index\",name=\"_get_rules_for_room\",instance=\"$instance\"}[$bucket_size]))/sum(rate(synapse_util_caches_cache{job=\"$job\",index=~\"$index\", name=\"_get_rules_for_room\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
               "legendFormat": "Hit Rate",
-              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter",
+              "metric": "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter_total",
               "refId": "A",
               "step": 2
             },
@@ -5734,7 +5734,7 @@
                 "uid": "${DS_PROMETHEUS}"
               },
               "exemplar": true,
-              "expr": "sum(rate(synapse_util_caches_cache:total{job=\"$job\",index=~\"$index\", name=\"_get_rules_for_room\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_util_caches_cache{job=\"$job\",index=~\"$index\", name=\"_get_rules_for_room\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -6087,7 +6087,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "topk(10, rate(synapse_storage_transaction_time_count{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]))",
+              "expr": "topk(10, rate(synapse_storage_transaction_time_count_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -6187,7 +6187,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_storage_transaction_time_sum{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_storage_transaction_time_sum_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "instant": false,
               "interval": "",
@@ -6287,7 +6287,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_storage_transaction_time_sum{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])/rate(synapse_storage_transaction_time_count{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_storage_transaction_time_sum_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])/rate(synapse_storage_transaction_time_count_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "instant": false,
               "interval": "",
@@ -6538,7 +6538,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_metrics_block_ru_utime_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\",block_name!=\"wrapped_request_handler\"}[$bucket_size]) + rate(synapse_util_metrics_block_ru_stime_seconds[$bucket_size])",
+              "expr": "rate(synapse_util_metrics_block_ru_utime_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\",block_name!=\"wrapped_request_handler\"}[$bucket_size]) + rate(synapse_util_metrics_block_ru_stime_seconds_total[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -6636,7 +6636,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "(rate(synapse_util_metrics_block_ru_utime_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) + rate(synapse_util_metrics_block_ru_stime_seconds[$bucket_size])) / rate(synapse_util_metrics_block_count[$bucket_size])",
+              "expr": "(rate(synapse_util_metrics_block_ru_utime_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) + rate(synapse_util_metrics_block_ru_stime_seconds_total[$bucket_size])) / rate(synapse_util_metrics_block_count_total[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -6737,7 +6737,7 @@
                 "uid": "${DS_PROMETHEUS}"
               },
               "exemplar": true,
-              "expr": "rate(synapse_util_metrics_block_db_txn_duration_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_util_metrics_block_db_txn_duration_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -6839,7 +6839,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_metrics_block_db_txn_duration_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) / rate(synapse_util_metrics_block_db_txn_count{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_util_metrics_block_db_txn_duration_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) / rate(synapse_util_metrics_block_db_txn_count_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -6936,7 +6936,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_metrics_block_db_txn_duration_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) / rate(synapse_util_metrics_block_db_txn_count{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_util_metrics_block_db_txn_duration_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) / rate(synapse_util_metrics_block_db_txn_count_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -7033,7 +7033,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_metrics_block_time_seconds{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) / rate(synapse_util_metrics_block_count{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_util_metrics_block_time_seconds_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]) / rate(synapse_util_metrics_block_count_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -7122,7 +7122,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_metrics_block_count{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_util_metrics_block_count_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "interval": "",
               "legendFormat": "{{job}}-{{index}} {{block_name}}",
               "refId": "A"
@@ -7246,7 +7246,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_caches_cache:hits{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])/rate(synapse_util_caches_cache:total{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
+              "expr": "rate(synapse_util_caches_cache_hits{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])/rate(synapse_util_caches_cache{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
               "format": "time_series",
               "intervalFactor": 2,
               "legendFormat": "{{name}} {{job}}-{{index}}",
@@ -7347,7 +7347,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "synapse_util_caches_cache:size{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}",
+              "expr": "synapse_util_caches_cache_size{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}",
               "format": "time_series",
               "hide": false,
               "interval": "",
@@ -7447,7 +7447,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_caches_cache:total{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
+              "expr": "rate(synapse_util_caches_cache{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -7547,7 +7547,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "topk(10, rate(synapse_util_caches_cache:total{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size]) - rate(synapse_util_caches_cache:hits{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size]))",
+              "expr": "topk(10, rate(synapse_util_caches_cache{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size]) - rate(synapse_util_caches_cache_hits{job=~\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size]))",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 2,
@@ -7643,7 +7643,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_caches_cache:evicted_size{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_util_caches_cache_evicted_size{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size])",
               "format": "time_series",
               "interval": "",
               "intervalFactor": 1,
@@ -7763,7 +7763,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "synapse_util_caches_response_cache:size{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}",
+              "expr": "synapse_util_caches_response_cache_size{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}",
               "interval": "",
               "legendFormat": "{{name}} {{job}}-{{index}}",
               "refId": "A"
@@ -7853,7 +7853,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_util_caches_response_cache:hits{instance=\"$instance\", job=~\"$job\", index=~\"$index\"}[$bucket_size])/rate(synapse_util_caches_response_cache:total{instance=\"$instance\", job=~\"$job\", index=~\"$index\"}[$bucket_size])",
+              "expr": "rate(synapse_util_caches_response_cache_hits{instance=\"$instance\", job=~\"$job\", index=~\"$index\"}[$bucket_size])/rate(synapse_util_caches_response_cache{instance=\"$instance\", job=~\"$job\", index=~\"$index\"}[$bucket_size])",
               "interval": "",
               "legendFormat": "{{name}} {{job}}-{{index}}",
               "refId": "A"
@@ -9556,7 +9556,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "synapse_forward_extremities_bucket{instance=\"$instance\"} and on (index, instance, job) (synapse_storage_events_persisted_events > 0)",
+              "expr": "synapse_forward_extremities_bucket{instance=\"$instance\"} and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0)",
               "format": "heatmap",
               "intervalFactor": 1,
               "legendFormat": "{{le}}",
@@ -9716,7 +9716,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0)",
+              "expr": "rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0)",
               "format": "heatmap",
               "intervalFactor": 1,
               "legendFormat": "{{le}}",
@@ -9793,7 +9793,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "histogram_quantile(0.5, rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0))",
+              "expr": "histogram_quantile(0.5, rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "50%",
@@ -9803,7 +9803,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "histogram_quantile(0.75, rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0))",
+              "expr": "histogram_quantile(0.75, rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "75%",
@@ -9813,7 +9813,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "histogram_quantile(0.90, rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0))",
+              "expr": "histogram_quantile(0.90, rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "90%",
@@ -9823,7 +9823,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "histogram_quantile(0.99, rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0))",
+              "expr": "histogram_quantile(0.99, rate(synapse_storage_events_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "99%",
@@ -9905,7 +9905,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0)",
+              "expr": "rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0)",
               "format": "heatmap",
               "intervalFactor": 1,
               "legendFormat": "{{le}}",
@@ -9982,7 +9982,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "histogram_quantile(0.5, rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0))",
+              "expr": "histogram_quantile(0.5, rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "50%",
@@ -9992,7 +9992,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "histogram_quantile(0.75, rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0))",
+              "expr": "histogram_quantile(0.75, rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "75%",
@@ -10002,7 +10002,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "histogram_quantile(0.90, rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0))",
+              "expr": "histogram_quantile(0.90, rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "90%",
@@ -10012,7 +10012,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "histogram_quantile(0.99, rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events > 0))",
+              "expr": "histogram_quantile(0.99, rate(synapse_storage_events_stale_forward_extremities_persisted_bucket{instance=\"$instance\"}[$bucket_size]) and on (index, instance, job) (synapse_storage_events_persisted_events_total > 0))",
               "format": "time_series",
               "intervalFactor": 1,
               "legendFormat": "99%",
@@ -10297,7 +10297,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_storage_events_state_resolutions_during_persistence{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_storage_events_state_resolutions_during_persistence_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]))",
               "interval": "",
               "legendFormat": "State res ",
               "refId": "A"
@@ -10306,7 +10306,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_storage_events_potential_times_prune_extremities{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_storage_events_potential_times_prune_extremities_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]))",
               "interval": "",
               "legendFormat": "Potential to prune",
               "refId": "B"
@@ -10315,7 +10315,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "sum(rate(synapse_storage_events_times_pruned_extremities{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]))",
+              "expr": "sum(rate(synapse_storage_events_times_pruned_extremities_total{instance=\"$instance\",job=~\"$job\",index=~\"$index\"}[$bucket_size]))",
               "interval": "",
               "legendFormat": "Pruned",
               "refId": "C"
@@ -11069,7 +11069,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_handler_presence_notified_presence{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
+              "expr": "rate(synapse_handler_presence_notified_presence_total{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
               "interval": "",
               "legendFormat": "Notified",
               "refId": "A"
@@ -11078,7 +11078,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_handler_presence_federation_presence_out{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
+              "expr": "rate(synapse_handler_presence_federation_presence_out_total{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
               "interval": "",
               "legendFormat": "Remote ping",
               "refId": "B"
@@ -11087,7 +11087,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_handler_presence_presence_updates{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
+              "expr": "rate(synapse_handler_presence_presence_updates_total{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
               "interval": "",
               "legendFormat": "Total updates",
               "refId": "C"
@@ -11096,7 +11096,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_handler_presence_federation_presence{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
+              "expr": "rate(synapse_handler_presence_federation_presence_total{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
               "interval": "",
               "legendFormat": "Remote updates",
               "refId": "D"
@@ -11105,7 +11105,7 @@
               "datasource": {
                 "uid": "$datasource"
               },
-              "expr": "rate(synapse_handler_presence_bump_active_time{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
+              "expr": "rate(synapse_handler_presence_bump_active_time_total{job=\"$job\",index=~\"$index\",instance=\"$instance\"}[$bucket_size])",
               "interval": "",
               "legendFormat": "Bump active time",
               "refId": "E"
@@ -11789,7 +11789,7 @@
         "name": "instance",
         "options": [],
         "query": {
-          "query": "label_values(synapse_util_metrics_block_ru_utime_seconds, instance)",
+          "query": "label_values(synapse_util_metrics_block_ru_utime_seconds_total, instance)",
           "refId": "Prometheus-instance-Variable-Query"
         },
         "refresh": 2,
@@ -11818,7 +11818,7 @@
         "name": "job",
         "options": [],
         "query": {
-          "query": "label_values(synapse_util_metrics_block_ru_utime_seconds, job)",
+          "query": "label_values(synapse_util_metrics_block_ru_utime_seconds_total, job)",
           "refId": "Prometheus-job-Variable-Query"
         },
         "refresh": 2,
@@ -11848,7 +11848,7 @@
         "name": "index",
         "options": [],
         "query": {
-          "query": "label_values(synapse_util_metrics_block_ru_utime_seconds, index)",
+          "query": "label_values(synapse_util_metrics_block_ru_utime_seconds_total, index)",
           "refId": "Prometheus-index-Variable-Query"
         },
         "refresh": 2,
@@ -11896,6 +11896,6 @@
   "timezone": "",
   "title": "Synapse",
   "uid": "000000012",
-  "version": 132,
+  "version": 133,
   "weekStart": ""
-}
\ No newline at end of file
+}
diff --git a/contrib/prometheus/synapse-v1.rules b/contrib/prometheus/synapse-v1.rules
deleted file mode 100644
index 4c900ba537e1..000000000000
--- a/contrib/prometheus/synapse-v1.rules
+++ /dev/null
@@ -1,21 +0,0 @@
-synapse_federation_transaction_queue_pendingEdus:total = sum(synapse_federation_transaction_queue_pendingEdus or absent(synapse_federation_transaction_queue_pendingEdus)*0)
-synapse_federation_transaction_queue_pendingPdus:total = sum(synapse_federation_transaction_queue_pendingPdus or absent(synapse_federation_transaction_queue_pendingPdus)*0)
-
-synapse_http_server_request_count:method{servlet=""} = sum(synapse_http_server_request_count) by (method)
-synapse_http_server_request_count:servlet{method=""} = sum(synapse_http_server_request_count) by (servlet)
-
-synapse_http_server_request_count:total{servlet=""} = sum(synapse_http_server_request_count:by_method) by (servlet)
-
-synapse_cache:hit_ratio_5m = rate(synapse_util_caches_cache:hits[5m]) / rate(synapse_util_caches_cache:total[5m])
-synapse_cache:hit_ratio_30s = rate(synapse_util_caches_cache:hits[30s]) / rate(synapse_util_caches_cache:total[30s])
-
-synapse_federation_client_sent{type="EDU"} = synapse_federation_client_sent_edus + 0
-synapse_federation_client_sent{type="PDU"} = synapse_federation_client_sent_pdu_destinations:count + 0
-synapse_federation_client_sent{type="Query"} = sum(synapse_federation_client_sent_queries) by (job)
-
-synapse_federation_server_received{type="EDU"} = synapse_federation_server_received_edus + 0
-synapse_federation_server_received{type="PDU"} = synapse_federation_server_received_pdus + 0
-synapse_federation_server_received{type="Query"} = sum(synapse_federation_server_received_queries) by (job)
-
-synapse_federation_transaction_queue_pending{type="EDU"} = synapse_federation_transaction_queue_pending_edus + 0
-synapse_federation_transaction_queue_pending{type="PDU"} = synapse_federation_transaction_queue_pending_pdus + 0
diff --git a/contrib/prometheus/synapse-v2.rules b/contrib/prometheus/synapse-v2.rules
index 7e405bf7f0fe..cbe6f7bebaa4 100644
--- a/contrib/prometheus/synapse-v2.rules
+++ b/contrib/prometheus/synapse-v2.rules
@@ -1,55 +1,35 @@
 groups:
 - name: synapse
   rules:
-  - record: "synapse_federation_transaction_queue_pendingEdus:total"
-    expr: "sum(synapse_federation_transaction_queue_pendingEdus or absent(synapse_federation_transaction_queue_pendingEdus)*0)"
-  - record: "synapse_federation_transaction_queue_pendingPdus:total"
-    expr:   "sum(synapse_federation_transaction_queue_pendingPdus or absent(synapse_federation_transaction_queue_pendingPdus)*0)"
-  - record: 'synapse_http_server_request_count:method'
-    labels:
-      servlet: ""
-    expr: "sum(synapse_http_server_request_count) by (method)"
-  - record: 'synapse_http_server_request_count:servlet'
-    labels:
-      method: ""
-    expr: 'sum(synapse_http_server_request_count) by (servlet)'
-
-  - record: 'synapse_http_server_request_count:total'
-    labels:
-      servlet: ""
-    expr: 'sum(synapse_http_server_request_count:by_method) by (servlet)'
-
-  - record: 'synapse_cache:hit_ratio_5m'
-    expr: 'rate(synapse_util_caches_cache:hits[5m]) / rate(synapse_util_caches_cache:total[5m])'
-  - record: 'synapse_cache:hit_ratio_30s'
-    expr: 'rate(synapse_util_caches_cache:hits[30s]) / rate(synapse_util_caches_cache:total[30s])'
-
+  # These 3 rules are used in the included Prometheus console
   - record: 'synapse_federation_client_sent'
     labels:
       type: "EDU"
-    expr: 'synapse_federation_client_sent_edus + 0'
+    expr: 'synapse_federation_client_sent_edus_total + 0'
   - record: 'synapse_federation_client_sent'
     labels:
       type: "PDU"
-    expr: 'synapse_federation_client_sent_pdu_destinations:count + 0'
+    expr: 'synapse_federation_client_sent_pdu_destinations_count_total + 0'
   - record: 'synapse_federation_client_sent'
     labels:
       type: "Query"
     expr: 'sum(synapse_federation_client_sent_queries) by (job)'
 
+  # These 3 rules are used in the included Prometheus console
   - record: 'synapse_federation_server_received'
     labels:
       type: "EDU"
-    expr: 'synapse_federation_server_received_edus + 0'
+    expr: 'synapse_federation_server_received_edus_total + 0'
   - record: 'synapse_federation_server_received'
     labels:
       type: "PDU"
-    expr: 'synapse_federation_server_received_pdus + 0'
+    expr: 'synapse_federation_server_received_pdus_total + 0'
   - record: 'synapse_federation_server_received'
     labels:
       type: "Query"
     expr: 'sum(synapse_federation_server_received_queries) by (job)'
 
+  # These 2 rules are used in the included Prometheus console
   - record: 'synapse_federation_transaction_queue_pending'
     labels:
       type: "EDU"
@@ -59,20 +39,25 @@ groups:
       type: "PDU"
     expr: 'synapse_federation_transaction_queue_pending_pdus + 0'
 
+  # These 3 rules are used in the included Grafana dashboard
   - record: synapse_storage_events_persisted_by_source_type
-    expr: sum without(type, origin_type, origin_entity) (synapse_storage_events_persisted_events_sep{origin_type="remote"})
+    expr: sum without(type, origin_type, origin_entity) (synapse_storage_events_persisted_events_sep_total{origin_type="remote"})
     labels:
       type: remote
   - record: synapse_storage_events_persisted_by_source_type
-    expr: sum without(type, origin_type, origin_entity) (synapse_storage_events_persisted_events_sep{origin_entity="*client*",origin_type="local"})
+    expr: sum without(type, origin_type, origin_entity) (synapse_storage_events_persisted_events_sep_total{origin_entity="*client*",origin_type="local"})
     labels:
       type: local
   - record: synapse_storage_events_persisted_by_source_type
-    expr: sum without(type, origin_type, origin_entity) (synapse_storage_events_persisted_events_sep{origin_entity!="*client*",origin_type="local"})
+    expr: sum without(type, origin_type, origin_entity) (synapse_storage_events_persisted_events_sep_total{origin_entity!="*client*",origin_type="local"})
     labels:
       type: bridges
+
+  # This rule is used in the included Grafana dashboard
   - record: synapse_storage_events_persisted_by_event_type
-    expr: sum without(origin_entity, origin_type) (synapse_storage_events_persisted_events_sep)
+    expr: sum without(origin_entity, origin_type) (synapse_storage_events_persisted_events_sep_total)
+
+  # This rule is used in the included Grafana dashboard
   - record: synapse_storage_events_persisted_by_origin
-    expr: sum without(type) (synapse_storage_events_persisted_events_sep)
+    expr: sum without(type) (synapse_storage_events_persisted_events_sep_total)
 
diff --git a/debian/build_virtualenv b/debian/build_virtualenv
index ed916ac97a4a..dd97e888ba76 100755
--- a/debian/build_virtualenv
+++ b/debian/build_virtualenv
@@ -61,7 +61,7 @@ dh_virtualenv \
     --extras="all,systemd,test" \
     --requirements="exported_requirements.txt"
 
-PACKAGE_BUILD_DIR="debian/matrix-synapse-py3"
+PACKAGE_BUILD_DIR="$(pwd)/debian/matrix-synapse-py3"
 VIRTUALENV_DIR="${PACKAGE_BUILD_DIR}${DH_VIRTUALENV_INSTALL_ROOT}/matrix-synapse"
 TARGET_PYTHON="${VIRTUALENV_DIR}/bin/python"
 
@@ -78,9 +78,14 @@ case "$DEB_BUILD_OPTIONS" in
 
         cp -r tests "$tmpdir"
 
+        # To avoid pulling in the unbuilt Synapse in the local directory
+        pushd /
+
         PYTHONPATH="$tmpdir" \
             "${TARGET_PYTHON}" -m twisted.trial --reporter=text -j2 tests
 
+        popd
+
         ;;
 esac
 
diff --git a/debian/changelog b/debian/changelog
index 77c8f7ad0b7a..1c1545469fb0 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,21 @@
+matrix-synapse-py3 (1.68.0) stable; urgency=medium
+
+  * New Synapse release 1.68.0.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 27 Sep 2022 12:02:09 +0100
+
+matrix-synapse-py3 (1.68.0~rc2) stable; urgency=medium
+
+  * New Synapse release 1.68.0rc2.
+
+ -- Synapse Packaging team <packages@matrix.org>  Fri, 23 Sep 2022 09:40:10 +0100
+
+matrix-synapse-py3 (1.68.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.68.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 20 Sep 2022 11:18:20 +0100
+
 matrix-synapse-py3 (1.67.0) stable; urgency=medium
 
   * New Synapse release 1.67.0.
@@ -22,11 +40,15 @@ matrix-synapse-py3 (1.66.0) stable; urgency=medium
 
 matrix-synapse-py3 (1.66.0~rc2+nmu1) UNRELEASED; urgency=medium
 
+  [ Jörg Behrmann ]
   * Update debhelper to compatibility level 12.
   * Drop the preinst script stopping synapse.
   * Allocate a group for the system user.
   * Change dpkg-statoverride to --force-statoverride-add.
 
+  [ Erik Johnston ]
+  * Disable `dh_auto_configure` as it broke during Rust build.
+
  -- Jörg Behrmann <behrmann@physik.fu-berlin.de>  Tue, 23 Aug 2022 17:17:00 +0100
 
 matrix-synapse-py3 (1.66.0~rc2) stable; urgency=medium
diff --git a/debian/rules b/debian/rules
index 3b79d560744f..914d068f2abd 100755
--- a/debian/rules
+++ b/debian/rules
@@ -12,6 +12,8 @@ override_dh_installsystemd:
 # we don't really want to strip the symbols from our object files.
 override_dh_strip:
 
+override_dh_auto_configure:
+
 # many libraries pulled from PyPI have allocatable sections after
 # non-allocatable ones on which dwz errors out. For those without the issue the
 # gains are only marginal
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 90b1d9b09163..f4e61f9e674f 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -31,7 +31,9 @@ ARG PYTHON_VERSION=3.9
 ###
 ### Stage 0: generate requirements.txt
 ###
-FROM docker.io/python:${PYTHON_VERSION}-slim as requirements
+# We hardcode the use of Debian bullseye here because this could change upstream
+# and other Dockerfiles used for testing are expecting bullseye.
+FROM docker.io/python:${PYTHON_VERSION}-slim-bullseye as requirements
 
 # RUN --mount is specific to buildkit and is documented at
 # https://github.com/moby/buildkit/blob/master/frontend/dockerfile/docs/syntax.md#build-mounts-run---mount.
@@ -76,7 +78,7 @@ RUN if [ -z "$TEST_ONLY_IGNORE_POETRY_LOCKFILE" ]; then \
 ###
 ### Stage 1: builder
 ###
-FROM docker.io/python:${PYTHON_VERSION}-slim as builder
+FROM docker.io/python:${PYTHON_VERSION}-slim-bullseye as builder
 
 # install the OS build deps
 RUN \
@@ -93,11 +95,19 @@ RUN \
     libxml++2.6-dev \
     libxslt1-dev \
     openssl \
-    rustc \
     zlib1g-dev \
     git \
+    curl \
     && rm -rf /var/lib/apt/lists/*
 
+# Install rust and ensure its in the PATH
+ENV RUSTUP_HOME=/rust
+ENV CARGO_HOME=/cargo
+ENV PATH=/cargo/bin:/rust/bin:$PATH
+RUN mkdir /rust /cargo
+
+RUN curl -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path --default-toolchain stable
+
 # Beeper: install shared secret authenticator
 RUN pip install --prefix="/install" --no-deps --no-warn-script-location \
    'git+https://github.com/devture/matrix-synapse-shared-secret-auth@e178353ec87c56e0169dd04466d4769da5ed9c46#egg=shared_secret_authenticator'
@@ -113,8 +123,9 @@ RUN --mount=type=cache,target=/root/.cache/pip \
 
 # Copy over the rest of the synapse source code.
 COPY synapse /synapse/synapse/
+COPY rust /synapse/rust/
 # ... and what we need to `pip install`.
-COPY pyproject.toml README.rst /synapse/
+COPY pyproject.toml README.rst build_rust.py /synapse/
 
 # Repeat of earlier build argument declaration, as this is a new build stage.
 ARG TEST_ONLY_IGNORE_POETRY_LOCKFILE
@@ -132,7 +143,7 @@ RUN if [ -z "$TEST_ONLY_IGNORE_POETRY_LOCKFILE" ]; then \
 ### Stage 2: runtime
 ###
 
-FROM docker.io/python:${PYTHON_VERSION}-slim
+FROM docker.io/python:${PYTHON_VERSION}-slim-bullseye
 
 LABEL org.opencontainers.image.url='https://matrix.org/docs/projects/server/synapse'
 LABEL org.opencontainers.image.documentation='https://github.com/matrix-org/synapse/blob/master/docker/README.md'
diff --git a/docker/Dockerfile-custom-base b/docker/Dockerfile-custom-base
index 04fa7235fcf2..8b01e7f6c860 100644
--- a/docker/Dockerfile-custom-base
+++ b/docker/Dockerfile-custom-base
@@ -53,7 +53,7 @@ RUN \
     libxml++2.6-dev \
     libxslt1-dev \
     openssl \
-    rustc \
+    curl \
     zlib1g-dev \
     && rm -rf /var/lib/apt/lists/*
 
@@ -90,6 +90,14 @@ RUN cat /synapse/requirements-with-setuptools.txt | grep -v "setuptools==" > /sy
 RUN --mount=type=cache,target=/root/.cache/pip \
   pip install --prefix="/install" --no-deps --no-warn-script-location -r /synapse/requirements.txt
 
+# Install rust and ensure its in the PATH
+ENV RUSTUP_HOME=/rust
+ENV CARGO_HOME=/cargo
+ENV PATH=/cargo/bin:/rust/bin:$PATH
+RUN mkdir /rust /cargo
+
+RUN curl -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path --default-toolchain stable
+
 # Beeper: install shared secret authenticator
 RUN pip install --prefix="/install" --no-deps --no-warn-script-location \
    'git+https://github.com/devture/matrix-synapse-shared-secret-auth@e178353ec87c56e0169dd04466d4769da5ed9c46#egg=shared_secret_authenticator'
diff --git a/docker/Dockerfile-dhvirtualenv b/docker/Dockerfile-dhvirtualenv
index fbc1d2346fb8..ca3a259081c3 100644
--- a/docker/Dockerfile-dhvirtualenv
+++ b/docker/Dockerfile-dhvirtualenv
@@ -72,6 +72,7 @@ RUN apt-get update -qq -o Acquire::Languages=none \
     && env DEBIAN_FRONTEND=noninteractive apt-get install \
         -yqq --no-install-recommends -o Dpkg::Options::=--force-unsafe-io \
         build-essential \
+        curl \
         debhelper \
         devscripts \
         libsystemd-dev \
@@ -85,6 +86,15 @@ RUN apt-get update -qq -o Acquire::Languages=none \
         libpq-dev \
         xmlsec1
 
+# Install rust and ensure it's in the PATH
+ENV RUSTUP_HOME=/rust
+ENV CARGO_HOME=/cargo
+ENV PATH=/cargo/bin:/rust/bin:$PATH
+RUN mkdir /rust /cargo
+
+RUN curl -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path --default-toolchain stable
+
+
 COPY --from=builder /dh-virtualenv_1.2.2-1_all.deb /
 
 # install dhvirtualenv. Update the apt cache again first, in case we got a
diff --git a/docker/complement/Dockerfile b/docker/complement/Dockerfile
index 3cfff19f9acd..0e13722d1c00 100644
--- a/docker/complement/Dockerfile
+++ b/docker/complement/Dockerfile
@@ -17,26 +17,24 @@ ARG SYNAPSE_VERSION=latest
 # the same debian version as Synapse's docker image (so the versions of the
 # shared libraries match).
 
-FROM postgres:13-bullseye AS postgres_base
-    # initialise the database cluster in /var/lib/postgresql
-    RUN gosu postgres initdb --locale=C --encoding=UTF-8 --auth-host password
-
-    # Configure a password and create a database for Synapse
-    RUN echo "ALTER USER postgres PASSWORD 'somesecret'" | gosu postgres postgres --single
-    RUN echo "CREATE DATABASE synapse" | gosu postgres postgres --single
-
 # now build the final image, based on the Synapse image.
 
 FROM matrixdotorg/synapse-workers:$SYNAPSE_VERSION
     # copy the postgres installation over from the image we built above
     RUN adduser --system --uid 999 postgres --home /var/lib/postgresql
-    COPY --from=postgres_base /var/lib/postgresql /var/lib/postgresql
-    COPY --from=postgres_base /usr/lib/postgresql /usr/lib/postgresql
-    COPY --from=postgres_base /usr/share/postgresql /usr/share/postgresql
+    COPY --from=postgres:13-bullseye /usr/lib/postgresql /usr/lib/postgresql
+    COPY --from=postgres:13-bullseye /usr/share/postgresql /usr/share/postgresql
     RUN mkdir /var/run/postgresql && chown postgres /var/run/postgresql
     ENV PATH="${PATH}:/usr/lib/postgresql/13/bin"
     ENV PGDATA=/var/lib/postgresql/data
 
+    # initialise the database cluster in /var/lib/postgresql
+    RUN gosu postgres initdb --locale=C --encoding=UTF-8 --auth-host password
+
+    # Configure a password and create a database for Synapse
+    RUN echo "ALTER USER postgres PASSWORD 'somesecret'" | gosu postgres postgres --single
+    RUN echo "CREATE DATABASE synapse" | gosu postgres postgres --single
+
     # Extend the shared homeserver config to disable rate-limiting,
     # set Complement's static shared secret, enable registration, amongst other
     # tweaks to get Synapse ready for testing.
diff --git a/docs/admin_api/rooms.md b/docs/admin_api/rooms.md
index 7526956bec39..8f727b363eb8 100644
--- a/docs/admin_api/rooms.md
+++ b/docs/admin_api/rooms.md
@@ -393,6 +393,151 @@ A response body like the following is returned:
 }
 ```
 
+# Room Messages API
+
+The Room Messages admin API allows server admins to get all messages
+sent to a room in a given timeframe. There are various parameters available
+that allow for filtering and ordering the returned list. This API supports pagination.
+
+To use it, you will need to authenticate by providing an `access_token`
+for a server admin: see [Admin API](../usage/administration/admin_api).
+
+This endpoint mirrors the [Matrix Spec defined Messages API](https://spec.matrix.org/v1.1/client-server-api/#get_matrixclientv3roomsroomidmessages).
+
+The API is:
+```
+GET /_synapse/admin/v1/rooms/<room_id>/messages
+```
+
+**Parameters**
+
+The following path parameters are required:
+
+* `room_id` - The ID of the room you wish you fetch messages from.
+
+The following query parameters are available:
+
+* `from` (required) - The token to start returning events from. This token can be obtained from a prev_batch
+  or next_batch token returned by the /sync endpoint, or from an end token returned by a previous request to this endpoint.
+* `to` - The token to spot returning events at.
+* `limit` - The maximum number of events to return. Defaults to `10`.
+* `filter` - A JSON RoomEventFilter to filter returned events with.
+* `dir` - The direction to return events from. Either `f` for forwards or `b` for backwards. Setting
+  this value to `b` will reverse the above sort order. Defaults to `f`.
+
+**Response**
+
+The following fields are possible in the JSON response body:
+
+* `chunk` - A list of room events. The order depends on the dir parameter.
+          Note that an empty chunk does not necessarily imply that no more events are available. Clients should continue to paginate until no end property is returned.
+* `end` - A token corresponding to the end of chunk. This token can be passed back to this endpoint to request further events.
+          If no further events are available, this property is omitted from the response.
+* `start` - A token corresponding to the start of chunk.
+* `state` - A list of state events relevant to showing the chunk.
+
+**Example**
+
+For more details on each chunk, read [the Matrix specification](https://spec.matrix.org/v1.1/client-server-api/#get_matrixclientv3roomsroomidmessages).
+
+```json
+{
+  "chunk": [
+    {
+      "content": {
+        "body": "This is an example text message",
+        "format": "org.matrix.custom.html",
+        "formatted_body": "<b>This is an example text message</b>",
+        "msgtype": "m.text"
+      },
+      "event_id": "$143273582443PhrSn:example.org",
+      "origin_server_ts": 1432735824653,
+      "room_id": "!636q39766251:example.com",
+      "sender": "@example:example.org",
+      "type": "m.room.message",
+      "unsigned": {
+        "age": 1234
+      }
+    },
+    {
+      "content": {
+        "name": "The room name"
+      },
+      "event_id": "$143273582443PhrSn:example.org",
+      "origin_server_ts": 1432735824653,
+      "room_id": "!636q39766251:example.com",
+      "sender": "@example:example.org",
+      "state_key": "",
+      "type": "m.room.name",
+      "unsigned": {
+        "age": 1234
+      }
+    },
+    {
+      "content": {
+        "body": "Gangnam Style",
+        "info": {
+          "duration": 2140786,
+          "h": 320,
+          "mimetype": "video/mp4",
+          "size": 1563685,
+          "thumbnail_info": {
+            "h": 300,
+            "mimetype": "image/jpeg",
+            "size": 46144,
+            "w": 300
+          },
+          "thumbnail_url": "mxc://example.org/FHyPlCeYUSFFxlgbQYZmoEoe",
+          "w": 480
+        },
+        "msgtype": "m.video",
+        "url": "mxc://example.org/a526eYUSFFxlgbQYZmo442"
+      },
+      "event_id": "$143273582443PhrSn:example.org",
+      "origin_server_ts": 1432735824653,
+      "room_id": "!636q39766251:example.com",
+      "sender": "@example:example.org",
+      "type": "m.room.message",
+      "unsigned": {
+        "age": 1234
+      }
+    }
+  ],
+  "end": "t47409-4357353_219380_26003_2265",
+  "start": "t47429-4392820_219380_26003_2265"
+}
+```
+
+# Room Timestamp to Event API
+
+The Room Timestamp to Event API endpoint fetches the `event_id` of the closest event to the given
+timestamp (`ts` query parameter) in the given direction (`dir` query parameter).
+
+Useful for cases like jump to date so you can start paginating messages from
+a given date in the archive.
+
+The API is:
+```
+  GET /_synapse/admin/v1/rooms/<room_id>/timestamp_to_event
+```
+
+**Parameters**
+
+The following path parameters are required:
+
+* `room_id` - The ID of the room you wish to check.
+
+The following query parameters are available:
+
+* `ts` - a timestamp in milliseconds where we will find the closest event in
+  the given direction.
+* `dir` - can be `f` or `b` to indicate forwards and backwards in time from the
+  given timestamp. Defaults to `f`.
+
+**Response**
+
+* `event_id` - converted from timestamp
+
 # Block Room API
 The Block Room admin API allows server admins to block and unblock rooms,
 and query to see if a given room is blocked.
diff --git a/docs/admin_api/user_admin_api.md b/docs/admin_api/user_admin_api.md
index c1ca0c8a64d9..3625c7b6c5f5 100644
--- a/docs/admin_api/user_admin_api.md
+++ b/docs/admin_api/user_admin_api.md
@@ -42,6 +42,7 @@ It returns a JSON body like the following:
     "appservice_id": null,
     "consent_server_notice_sent": null,
     "consent_version": null,
+    "consent_ts": null,
     "external_ids": [
         {
             "auth_provider": "<provider1>",
@@ -364,6 +365,7 @@ The following actions are **NOT** performed. The list may be incomplete.
 - Remove the user's creation (registration) timestamp
 - [Remove rate limit overrides](#override-ratelimiting-for-users)
 - Remove from monthly active users
+- Remove user's consent information (consent version and timestamp)
 
 ## Reset password
 
@@ -1153,3 +1155,41 @@ GET /_synapse/admin/v1/username_available?username=$localpart
 
 The request and response format is the same as the
 [/_matrix/client/r0/register/available](https://matrix.org/docs/spec/client_server/r0.6.0#get-matrix-client-r0-register-available) API.
+
+### Find a user based on their ID in an auth provider
+
+The API is:
+
+```
+GET /_synapse/admin/v1/auth_providers/$provider/users/$external_id
+```
+
+When a user matched the given ID for the given provider, an HTTP code `200` with a response body like the following is returned:
+
+```json
+{
+    "user_id": "@hello:example.org"
+}
+```
+
+**Parameters**
+
+The following parameters should be set in the URL:
+
+- `provider` - The ID of the authentication provider, as advertised by the [`GET /_matrix/client/v3/login`](https://spec.matrix.org/latest/client-server-api/#post_matrixclientv3login) API in the `m.login.sso` authentication method.
+- `external_id` - The user ID from the authentication provider. Usually corresponds to the `sub` claim for OIDC providers, or to the `uid` attestation for SAML2 providers.
+
+The `external_id` may have characters that are not URL-safe (typically `/`, `:` or `@`), so it is advised to URL-encode those parameters.
+
+**Errors**
+
+Returns a `404` HTTP status code if no user was found, with a response body like this:
+
+```json
+{
+    "errcode":"M_NOT_FOUND",
+    "error":"User not found"
+}
+```
+
+_Added in Synapse 1.68.0._
diff --git a/docs/deprecation_policy.md b/docs/deprecation_policy.md
index 359dac07c3dc..46c18d7d3205 100644
--- a/docs/deprecation_policy.md
+++ b/docs/deprecation_policy.md
@@ -1,9 +1,9 @@
 Deprecation Policy for Platform Dependencies
 ============================================
 
-Synapse has a number of platform dependencies, including Python and PostgreSQL.
-This document outlines the policy towards which versions we support, and when we
-drop support for versions in the future.
+Synapse has a number of platform dependencies, including Python, Rust, 
+PostgreSQL and SQLite. This document outlines the policy towards which versions 
+we support, and when we drop support for versions in the future.
 
 
 Policy
@@ -17,6 +17,14 @@ Details on the upstream support life cycles for Python and PostgreSQL are
 documented at [https://endoflife.date/python](https://endoflife.date/python) and
 [https://endoflife.date/postgresql](https://endoflife.date/postgresql).
 
+A Rust compiler is required to build Synapse from source. For any given release
+the minimum required version may be bumped up to a recent Rust version, and so
+people building from source should ensure they can fetch recent versions of Rust
+(e.g. by using [rustup](https://rustup.rs/)).
+
+The oldest supported version of SQLite is the version
+[provided](https://packages.debian.org/buster/libsqlite3-0) by
+[Debian oldstable](https://wiki.debian.org/DebianOldStable).
 
 Context
 -------
@@ -31,3 +39,15 @@ long process.
 By following the upstream support life cycles Synapse can ensure that its
 dependencies continue to get security patches, while not requiring system admins
 to constantly update their platform dependencies to the latest versions.
+
+For Rust, the situation is a bit different given that a) the Rust foundation
+does not generally support older Rust versions, and b) the library ecosystem
+generally bump their minimum support Rust versions frequently. In general, the
+Synapse team will try to avoid updating the dependency on Rust to the absolute
+latest version, but introducing a formal policy is hard given the constraints of
+the ecosystem.
+
+On a similar note, SQLite does not generally have a concept of "supported 
+release"; bugfixes are published for the latest minor release only. We chose to
+track Debian's oldstable as this is relatively conservative, predictably updated
+and is consistent with the `.deb` packages released by Matrix.org.
\ No newline at end of file
diff --git a/docs/development/contributing_guide.md b/docs/development/contributing_guide.md
index 4e1df5116453..cb0d727efa63 100644
--- a/docs/development/contributing_guide.md
+++ b/docs/development/contributing_guide.md
@@ -28,6 +28,9 @@ The source code of Synapse is hosted on GitHub. You will also need [a recent ver
 
 For some tests, you will need [a recent version of Docker](https://docs.docker.com/get-docker/).
 
+A recent version of the Rust compiler is needed to build the native modules. The
+easiest way of installing the latest version is to use [rustup](https://rustup.rs/).
+
 
 # 3. Get the source.
 
@@ -114,6 +117,11 @@ Some documentation also exists in [Synapse's GitHub
 Wiki](https://github.com/matrix-org/synapse/wiki), although this is primarily
 contributed to by community authors.
 
+When changes are made to any Rust code then you must call either `poetry install`
+or `maturin develop` (if installed) to rebuild the Rust code. Using [`maturin`](https://github.com/PyO3/maturin)
+is quicker than `poetry install`, so is recommended when making frequent
+changes to the Rust code.
+
 
 # 8. Test, test, test!
 <a name="test-test-test"></a>
@@ -195,7 +203,7 @@ The database file can then be inspected with:
 sqlite3 _trial_temp/test.db
 ```
 
-Note that the database file is cleared at the beginning of each test run. Thus it 
+Note that the database file is cleared at the beginning of each test run. Thus it
 will always only contain the data generated by the *last run test*. Though generally
 when debugging, one is only running a single test anyway.
 
diff --git a/docs/development/dependencies.md b/docs/development/dependencies.md
index b356870f2795..8474525480d6 100644
--- a/docs/development/dependencies.md
+++ b/docs/development/dependencies.md
@@ -126,6 +126,23 @@ context of poetry's venv, without having to run `poetry shell` beforehand.
 poetry install --extras all --remove-untracked
 ```
 
+## ...delete everything and start over from scratch?
+
+```shell
+# Stop the current virtualenv if active
+$ deactivate
+
+# Remove all of the files from the current environment.
+# Don't worry, even though it says "all", this will only
+# remove the Poetry virtualenvs for the current project.
+$ poetry env remove --all
+
+# Reactivate Poetry shell to create the virtualenv again
+$ poetry shell
+# Install everything again
+$ poetry install --extras all
+```
+
 ## ...run a command in the `poetry` virtualenv?
 
 Use `poetry run cmd args` when you need the python virtualenv context.
@@ -256,6 +273,16 @@ from PyPI. (This is what makes poetry seem slow when doing the first
 `poetry install`.) Try `poetry cache list` and `poetry cache clear --all
 <name of cache>` to see if that fixes things.
 
+## Remove outdated egg-info
+
+Delete the `matrix_synapse.egg-info/` directory from the root of your Synapse
+install.
+
+This stores some cached information about dependencies and often conflicts with
+letting Poetry do the right thing.
+
+
+
 ## Try `--verbose` or `--dry-run` arguments.
 
 Sometimes useful to see what poetry's internal logic is.
diff --git a/docs/reverse_proxy.md b/docs/reverse_proxy.md
index d1618e815526..4e7a1d443533 100644
--- a/docs/reverse_proxy.md
+++ b/docs/reverse_proxy.md
@@ -45,6 +45,10 @@ listens to traffic on localhost. (Do not change `bind_addresses` to `127.0.0.1`
 when using a containerized Synapse, as that will prevent it from responding
 to proxied traffic.)
 
+Optionally, you can also set
+[`request_id_header`](../usage/configuration/config_documentation.md#listeners)
+so that the server extracts and re-uses the same request ID format that the
+reverse proxy is using.
 
 ## Reverse-proxy configuration examples
 
diff --git a/docs/setup/installation.md b/docs/setup/installation.md
index bb78b3267aae..96833effc6b9 100644
--- a/docs/setup/installation.md
+++ b/docs/setup/installation.md
@@ -196,6 +196,10 @@ System requirements:
 - Python 3.7 or later, up to Python 3.10.
 - At least 1GB of free RAM if you want to join large public rooms like #matrix:matrix.org
 
+If building on an uncommon architecture for which pre-built wheels are
+unavailable, you will need to have a recent Rust compiler installed. The easiest
+way of installing the latest version is to use [rustup](https://rustup.rs/).
+
 To install the Synapse homeserver run:
 
 ```sh
@@ -299,9 +303,10 @@ You may need to install the latest Xcode developer tools:
 xcode-select --install
 ```
 
-On ARM-based Macs you may need to explicitly install libjpeg which is a pillow dependency. You can use Homebrew (https://brew.sh):
+On ARM-based Macs you may need to install libjpeg and libpq. 
+You can use Homebrew (https://brew.sh):
 ```sh
- brew install jpeg
+ brew install jpeg libpq
  ```
 
 On macOS Catalina (10.15) you may need to explicitly install OpenSSL
diff --git a/docs/upgrade.md b/docs/upgrade.md
index 9f165551fa6d..37f1cb27df95 100644
--- a/docs/upgrade.md
+++ b/docs/upgrade.md
@@ -15,9 +15,8 @@ this document.
     The website <https://endoflife.date> also offers convenient
     summaries.
 
--   If Synapse was installed using [prebuilt
-    packages](setup/installation.md#prebuilt-packages), you will need to follow the
-    normal process for upgrading those packages.
+-   If Synapse was installed using [prebuilt packages](setup/installation.md#prebuilt-packages),
+    you will need to follow the normal process for upgrading those packages.
 
 -   If Synapse was installed using pip then upgrade to the latest
     version by running:
@@ -89,6 +88,20 @@ process, for example:
     dpkg -i matrix-synapse-py3_1.3.0+stretch1_amd64.deb
     ```
 
+# Upgrading to v1.68.0
+
+As announced in the upgrade notes for v1.67.0, Synapse now requires a SQLite
+version of 3.27.0 or higher if SQLite is in use and source checkouts of Synapse
+now require a recent Rust compiler.
+
+Installations using 
+
+- Docker images [from `matrixdotorg`](https://hub.docker.com/r/matrixdotorg/synapse),
+- Debian packages [from Matrix.org](https://packages.matrix.org/), or
+- PyPI wheels via `pip install matrix-synapse` (on supported platforms and architectures)
+
+will not be affected.
+
 # Upgrading to v1.67.0
 
 ## Direct TCP replication is no longer supported: migrate to Redis
@@ -125,7 +138,7 @@ From the next major release (v1.68.0) Synapse will require SQLite 3.27.0 or
 higher. Synapse v1.67.0 will be the last major release supporting SQLite
 versions 3.22 to 3.26.
 
-Those using docker images or Debian packages from Matrix.org will not be
+Those using Docker images or Debian packages from Matrix.org will not be
 affected. If you have installed from source, you should check the version of 
 SQLite used by Python with:
 
@@ -135,6 +148,7 @@ python -c "import sqlite3; print(sqlite3.sqlite_version)"
 
 If this is too old, refer to your distribution for advice on upgrading.
 
+
 # Upgrading to v1.66.0
 
 ## Delegation of email validation no longer supported
diff --git a/docs/usage/administration/request_log.md b/docs/usage/administration/request_log.md
index adb5f4f5f353..82f5ac7b96a5 100644
--- a/docs/usage/administration/request_log.md
+++ b/docs/usage/administration/request_log.md
@@ -12,14 +12,14 @@ See the following for how to decode the dense data available from the default lo
 
 | Part  | Explanation | 
 | ----- | ------------ |
-| AAAA  | Timestamp request was logged (not recieved) |
+| AAAA  | Timestamp request was logged (not received) |
 | BBBB  | Logger name (`synapse.access.(http\|https).<tag>`, where 'tag' is defined in the `listeners` config section, normally the port) |
 | CCCC  | Line number in code |
 | DDDD  | Log Level |
 | EEEE  | Request Identifier (This identifier is shared by related log lines)|
 | FFFF  | Source IP (Or X-Forwarded-For if enabled) |
 | GGGG  | Server Port |
-| HHHH  | Federated Server or Local User making request (blank if unauthenticated or not supplied) |
+| HHHH  | Federated Server or Local User making request (blank if unauthenticated or not supplied).<br/>If this is of the form `@aaa:example.com|@bbb:example.com`, then that means that `@aaa:example.com` is authenticated but they are controlling `@bbb:example.com`, e.g. if `aaa` is controlling `bbb` [via the admin API](https://matrix-org.github.io/synapse/latest/admin_api/user_admin_api.html#login-as-a-user). |
 | IIII  | Total Time to process the request |
 | JJJJ  | Time to send response over network once generated (this may be negative if the socket is closed before the response is generated)|
 | KKKK  | Userland CPU time |
diff --git a/docs/usage/configuration/config_documentation.md b/docs/usage/configuration/config_documentation.md
index 757957a1d58f..69d305b62e6d 100644
--- a/docs/usage/configuration/config_documentation.md
+++ b/docs/usage/configuration/config_documentation.md
@@ -434,7 +434,16 @@ Sub-options for each listener include:
 * `tls`: set to true to enable TLS for this listener. Will use the TLS key/cert specified in tls_private_key_path / tls_certificate_path.
 
 * `x_forwarded`: Only valid for an 'http' listener. Set to true to use the X-Forwarded-For header as the client IP. Useful when Synapse is
-   behind a reverse-proxy.
+   behind a [reverse-proxy](../../reverse_proxy.md).
+
+* `request_id_header`: The header extracted from each incoming request that is
+   used as the basis for the request ID. The request ID is used in
+   [logs](../administration/request_log.md#request-log-format) and tracing to
+   correlate and match up requests. When unset, Synapse will automatically
+   generate sequential request IDs. This option is useful when Synapse is behind
+   a [reverse-proxy](../../reverse_proxy.md).
+
+   _Added in Synapse 1.68.0._
 
 * `resources`: Only valid for an 'http' listener. A list of resources to host
    on this port. Sub-options for each resource are:
@@ -1069,8 +1078,10 @@ Options related to caching.
 ---
 ### `event_cache_size`
 
-The number of events to cache in memory. Not affected by
-`caches.global_factor` and is not part of the `caches` section. Defaults to 10K.
+The number of events to cache in memory. Defaults to 10K. Like other caches,
+this is affected by `caches.global_factor` (see below).
+
+Note that this option is not part of the `caches` section.
 
 Example configuration:
 ```yaml
@@ -1391,7 +1402,7 @@ This option specifies several limits for login:
   client is attempting to log into. Defaults to `per_second: 0.17`,
   `burst_count: 3`.
 
-* `failted_attempts` ratelimits login requests based on the account the
+* `failed_attempts` ratelimits login requests based on the account the
   client is attempting to log into, based on the amount of failed login
   attempts for this account. Defaults to `per_second: 0.17`, `burst_count: 3`.
 
diff --git a/mypy.ini b/mypy.ini
index e2034e411fa5..64f9097206d1 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -16,7 +16,8 @@ files =
   docker/,
   scripts-dev/,
   synapse/,
-  tests/
+  tests/,
+  build_rust.py
 
 # Note: Better exclusion syntax coming in mypy > 0.910
 # https://github.com/python/mypy/pull/11329
@@ -181,3 +182,6 @@ ignore_missing_imports = True
 
 [mypy-incremental.*]
 ignore_missing_imports = True
+
+[mypy-setuptools_rust.*]
+ignore_missing_imports = True
diff --git a/poetry.lock b/poetry.lock
index 6cc7a330d9b3..074147512c83 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -476,7 +476,7 @@ name = "jump-consistent-hash"
 version = "3.2.0"
 description = "Implementation of the Jump Consistent Hash algorithm"
 category = "main"
-optional = false
+optional = true
 python-versions = ">=3.6"
 
 [[package]]
@@ -532,11 +532,11 @@ python-versions = ">=3.7"
 
 [[package]]
 name = "matrix-common"
-version = "1.2.1"
+version = "1.3.0"
 description = "Common utilities for Synapse, Sydent and Sygnal"
 category = "main"
 optional = false
-python-versions = ">=3.6"
+python-versions = ">=3.7"
 
 [package.dependencies]
 attrs = "*"
@@ -1043,6 +1043,18 @@ python-versions = ">=3.6"
 cryptography = ">=2.0"
 jeepney = ">=0.6"
 
+[[package]]
+name = "semantic-version"
+version = "2.10.0"
+description = "A library implementing the 'SemVer' scheme."
+category = "main"
+optional = false
+python-versions = ">=2.7"
+
+[package.extras]
+dev = ["Django (>=1.11)", "check-manifest", "colorama (<=0.4.1)", "coverage", "flake8", "nose2", "readme-renderer (<25.0)", "tox", "wheel", "zest.releaser[recommended]"]
+doc = ["Sphinx", "sphinx-rtd-theme"]
+
 [[package]]
 name = "sentry-sdk"
 version = "1.5.11"
@@ -1107,6 +1119,19 @@ docs = ["furo", "jaraco.packaging (>=9)", "jaraco.tidelift (>=1.4)", "pygments-g
 testing = ["build[virtualenv]", "filelock (>=3.4.0)", "flake8 (<5)", "flake8-2020", "ini2toml[lite] (>=0.9)", "jaraco.envs (>=2.2)", "jaraco.path (>=3.2.0)", "mock", "pip (>=19.1)", "pip-run (>=8.8)", "pytest (>=6)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=2.4)", "pytest-cov", "pytest-enabler (>=1.3)", "pytest-flake8", "pytest-mypy (>=0.9.1)", "pytest-perf", "pytest-xdist", "tomli-w (>=1.0.0)", "virtualenv (>=13.0.0)", "wheel"]
 testing-integration = ["build[virtualenv]", "filelock (>=3.4.0)", "jaraco.envs (>=2.2)", "jaraco.path (>=3.2.0)", "pytest", "pytest-enabler", "pytest-xdist", "tomli", "virtualenv (>=13.0.0)", "wheel"]
 
+[[package]]
+name = "setuptools-rust"
+version = "1.5.1"
+description = "Setuptools Rust extension plugin"
+category = "main"
+optional = false
+python-versions = ">=3.7"
+
+[package.dependencies]
+semantic-version = ">=2.8.2,<3"
+setuptools = ">=62.4"
+typing-extensions = ">=3.7.4.3"
+
 [[package]]
 name = "signedjson"
 version = "1.1.4"
@@ -1608,7 +1633,7 @@ url_preview = ["lxml"]
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.7.1"
-content-hash = "a2106508f27d5476451fbc726e5fbe0bcfe9a91ff984ee583c2e63b6c6db1a54"
+content-hash = "50598280f4496145454cc790fdd9cc2f643af1ef6e3c8e7503497342bdab2f08"
 
 [metadata.files]
 attrs = [
@@ -2155,8 +2180,8 @@ markupsafe = [
     {file = "MarkupSafe-2.1.0.tar.gz", hash = "sha256:80beaf63ddfbc64a0452b841d8036ca0611e049650e20afcb882f5d3c266d65f"},
 ]
 matrix-common = [
-    {file = "matrix_common-1.2.1-py3-none-any.whl", hash = "sha256:946709c405944a0d4b1d73207b77eb064b6dbfc5d70a69471320b06d8ce98b20"},
-    {file = "matrix_common-1.2.1.tar.gz", hash = "sha256:a99dcf02a6bd95b24a5a61b354888a2ac92bf2b4b839c727b8dd9da2cdfa3853"},
+    {file = "matrix_common-1.3.0-py3-none-any.whl", hash = "sha256:524e2785b9b03be4d15f3a8a6b857c5b6af68791ffb1b9918f0ad299abc4db20"},
+    {file = "matrix_common-1.3.0.tar.gz", hash = "sha256:62e121cccd9f243417b57ec37a76dc44aeb198a7a5c67afd6b8275992ff2abd1"},
 ]
 matrix-synapse-ldap3 = [
     {file = "matrix-synapse-ldap3-0.2.2.tar.gz", hash = "sha256:b388d95693486eef69adaefd0fd9e84463d52fe17b0214a00efcaa669b73cb74"},
@@ -2546,6 +2571,10 @@ secretstorage = [
     {file = "SecretStorage-3.3.1-py3-none-any.whl", hash = "sha256:422d82c36172d88d6a0ed5afdec956514b189ddbfb72fefab0c8a1cee4eaf71f"},
     {file = "SecretStorage-3.3.1.tar.gz", hash = "sha256:fd666c51a6bf200643495a04abb261f83229dcb6fd8472ec393df7ffc8b6f195"},
 ]
+semantic-version = [
+    {file = "semantic_version-2.10.0-py2.py3-none-any.whl", hash = "sha256:de78a3b8e0feda74cabc54aab2da702113e33ac9d9eb9d2389bcf1f58b7d9177"},
+    {file = "semantic_version-2.10.0.tar.gz", hash = "sha256:bdabb6d336998cbb378d4b9db3a4b56a1e3235701dc05ea2690d9a997ed5041c"},
+]
 sentry-sdk = [
     {file = "sentry-sdk-1.5.11.tar.gz", hash = "sha256:6c01d9d0b65935fd275adc120194737d1df317dce811e642cbf0394d0d37a007"},
     {file = "sentry_sdk-1.5.11-py2.py3-none-any.whl", hash = "sha256:c17179183cac614e900cbd048dab03f49a48e2820182ec686c25e7ce46f8548f"},
@@ -2558,6 +2587,10 @@ setuptools = [
     {file = "setuptools-65.3.0-py3-none-any.whl", hash = "sha256:2e24e0bec025f035a2e72cdd1961119f557d78ad331bb00ff82efb2ab8da8e82"},
     {file = "setuptools-65.3.0.tar.gz", hash = "sha256:7732871f4f7fa58fb6bdcaeadb0161b2bd046c85905dbaa066bdcbcc81953b57"},
 ]
+setuptools-rust = [
+    {file = "setuptools-rust-1.5.1.tar.gz", hash = "sha256:0e05e456645d59429cb1021370aede73c0760e9360bbfdaaefb5bced530eb9d7"},
+    {file = "setuptools_rust-1.5.1-py3-none-any.whl", hash = "sha256:306b236ff3aa5229180e58292610d0c2c51bb488191122d2fc559ae4caeb7d5e"},
+]
 signedjson = [
     {file = "signedjson-1.1.4-py3-none-any.whl", hash = "sha256:45569ec54241c65d2403fe3faf7169be5322547706a231e884ca2b427f23d228"},
     {file = "signedjson-1.1.4.tar.gz", hash = "sha256:cd91c56af53f169ef032c62e9c4a3292dc158866933318d0592e3462db3d6492"},
diff --git a/pyproject.toml b/pyproject.toml
index 00f09e996a9d..a677470b01ea 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -52,9 +52,12 @@ include_trailing_comma = true
 combine_as_imports = true
 skip_gitignore = true
 
+[tool.maturin]
+manifest-path = "rust/Cargo.toml"
+
 [tool.poetry]
 name = "matrix-synapse"
-version = "1.67.0"
+version = "1.68.0"
 description = "Homeserver for the Matrix decentralised comms protocol"
 authors = ["Matrix.org Team and Contributors <packages@matrix.org>"]
 license = "Apache-2.0"
@@ -82,8 +85,18 @@ include = [
     { path = "sytest-blacklist", format = "sdist" },
     { path = "tests", format = "sdist" },
     { path = "UPGRADE.rst", format = "sdist" },
+    { path = "Cargo.toml", format = "sdist" },
+    { path = "Cargo.lock", format = "sdist" },
+    { path = "rust/Cargo.toml", format = "sdist" },
+    { path = "rust/build.rs", format = "sdist" },
+    { path = "rust/src/**", format = "sdist" },
+]
+exclude = [
+    { path = "synapse/*.so", format = "sdist"}
 ]
 
+build = "build_rust.py"
+
 [tool.poetry.scripts]
 synapse_homeserver = "synapse.app.homeserver:main"
 synapse_worker = "synapse.app.generic_worker:main"
@@ -126,7 +139,7 @@ pyOpenSSL = ">=16.0.0"
 PyYAML = ">=3.11"
 pyasn1 = ">=0.1.9"
 pyasn1-modules = ">=0.0.7"
-bcrypt = ">=3.1.0"
+bcrypt = ">=3.1.7"
 Pillow = ">=5.4.0"
 sortedcontainers = ">=1.4.4"
 pymacaroons = ">=0.13.0"
@@ -152,7 +165,7 @@ typing-extensions = ">=3.10.0.1"
 cryptography = ">=3.4.7"
 # ijson 3.1.4 fixes a bug with "." in property names
 ijson = ">=3.1.4"
-matrix-common = "^1.2.1"
+matrix-common = "^1.3.0"
 # We need packaging.requirements.Requirement, added in 16.1.
 packaging = ">=16.1"
 # At the time of writing, we only use functions from the version `importlib.metadata`
@@ -161,6 +174,15 @@ importlib_metadata = { version = ">=1.4", python = "<3.8" }
 # This is the most recent version of Pydantic with available on common distros.
 pydantic = ">=1.7.4"
 
+# This is for building the rust components during "poetry install", which
+# currently ignores the `build-system.requires` directive (c.f.
+# https://github.com/python-poetry/poetry/issues/6154). Both `pip install` and
+# `poetry build` do the right thing without this explicit dependency.
+#
+# This isn't really a dev-dependency, as `poetry install --no-dev` will fail,
+# but the alternative is to add it to the main list of deps where it isn't
+# needed.
+setuptools_rust = ">=1.3"
 
 
 # Optional Dependencies
@@ -185,7 +207,7 @@ hiredis = { version = "*", optional = true }
 Pympler = { version = "*", optional = true }
 parameterized = { version = ">=0.7.4", optional = true }
 idna = { version = ">=2.5", optional = true }
-jump-consistent-hash = "^3.2.0"
+jump-consistent-hash = { version = "^3.2.0", optional = true }
 
 [tool.poetry.extras]
 # NB: Packages that should be part of `pip install matrix-synapse[all]` need to be specified
@@ -286,5 +308,21 @@ twine = "*"
 towncrier = ">=18.6.0rc1"
 
 [build-system]
-requires = ["poetry-core>=1.0.0"]
+requires = ["poetry-core>=1.0.0", "setuptools_rust>=1.3"]
 build-backend = "poetry.core.masonry.api"
+
+
+[tool.cibuildwheel]
+# Skip unsupported platforms (by us or by Rust).
+skip = "cp36* *-musllinux_i686"
+
+# We need a rust compiler
+before-all =  "curl https://sh.rustup.rs -sSf | sh -s -- --default-toolchain stable -y"
+environment= { PATH = "$PATH:$HOME/.cargo/bin" }
+
+# For some reason if we don't manually clean the build directory we
+# can end up polluting the next build with a .so that is for the wrong
+# Python version.
+before-build = "rm -rf {project}/build"
+build-frontend = "build"
+test-command = "python -c 'from synapse.synapse_rust import sum_as_string; print(sum_as_string(1, 2))'"
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
new file mode 100644
index 000000000000..657f78c0b1e0
--- /dev/null
+++ b/rust/Cargo.toml
@@ -0,0 +1,25 @@
+[package]
+# We name the package `synapse` so that things like logging have the right
+# logging target.
+name = "synapse"
+
+# dummy version. See pyproject.toml for the Synapse's version number.
+version = "0.1.0"
+
+edition = "2021"
+rust-version = "1.58.1"
+
+[lib]
+name = "synapse"
+crate-type = ["cdylib"]
+
+[package.metadata.maturin]
+# This is where we tell maturin where to place the built library.
+name = "synapse.synapse_rust"
+
+[dependencies]
+pyo3 = { version = "0.16.5", features = ["extension-module", "macros", "abi3", "abi3-py37"] }
+
+[build-dependencies]
+blake2 = "0.10.4"
+hex = "0.4.3"
diff --git a/rust/build.rs b/rust/build.rs
new file mode 100644
index 000000000000..2117975e56f7
--- /dev/null
+++ b/rust/build.rs
@@ -0,0 +1,45 @@
+//! This build script calculates the hash of all files in the `src/`
+//! directory and adds it as an environment variable during build time.
+//!
+//! This is used so that the python code can detect when the built native module
+//! does not match the source in-tree, helping to detect the case where the
+//! source has been updated but the library hasn't been rebuilt.
+
+use std::path::PathBuf;
+
+use blake2::{Blake2b512, Digest};
+
+fn main() -> Result<(), std::io::Error> {
+    let mut dirs = vec![PathBuf::from("src")];
+
+    let mut paths = Vec::new();
+    while let Some(path) = dirs.pop() {
+        let mut entries = std::fs::read_dir(path)?
+            .map(|res| res.map(|e| e.path()))
+            .collect::<Result<Vec<_>, std::io::Error>>()?;
+
+        entries.sort();
+
+        for entry in entries {
+            if entry.is_dir() {
+                dirs.push(entry)
+            } else {
+                paths.push(entry.to_str().expect("valid rust paths").to_string());
+            }
+        }
+    }
+
+    paths.sort();
+
+    let mut hasher = Blake2b512::new();
+
+    for path in paths {
+        let bytes = std::fs::read(path)?;
+        hasher.update(bytes);
+    }
+
+    let hex_digest = hex::encode(hasher.finalize());
+    println!("cargo:rustc-env=SYNAPSE_RUST_DIGEST={hex_digest}");
+
+    Ok(())
+}
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
new file mode 100644
index 000000000000..ba42465fb80b
--- /dev/null
+++ b/rust/src/lib.rs
@@ -0,0 +1,24 @@
+use pyo3::prelude::*;
+
+/// Returns the hash of all the rust source files at the time it was compiled.
+///
+/// Used by python to detect if the rust library is outdated.
+#[pyfunction]
+fn get_rust_file_digest() -> &'static str {
+    env!("SYNAPSE_RUST_DIGEST")
+}
+
+/// Formats the sum of two numbers as string.
+#[pyfunction]
+#[pyo3(text_signature = "(a, b, /)")]
+fn sum_as_string(a: usize, b: usize) -> PyResult<String> {
+    Ok((a + b).to_string())
+}
+
+/// The entry point for defining the Python module.
+#[pymodule]
+fn synapse_rust(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
+    m.add_function(wrap_pyfunction!(sum_as_string, m)?)?;
+    m.add_function(wrap_pyfunction!(get_rust_file_digest, m)?)?;
+    Ok(())
+}
diff --git a/scripts-dev/make_full_schema.sh b/scripts-dev/make_full_schema.sh
index f0e22d4ca25b..61394360cecb 100755
--- a/scripts-dev/make_full_schema.sh
+++ b/scripts-dev/make_full_schema.sh
@@ -9,8 +9,10 @@
 export PGHOST="localhost"
 POSTGRES_DB_NAME="synapse_full_schema.$$"
 
-SQLITE_FULL_SCHEMA_OUTPUT_FILE="full.sql.sqlite"
-POSTGRES_FULL_SCHEMA_OUTPUT_FILE="full.sql.postgres"
+SQLITE_SCHEMA_FILE="schema.sql.sqlite"
+SQLITE_ROWS_FILE="rows.sql.sqlite"
+POSTGRES_SCHEMA_FILE="full.sql.postgres"
+POSTGRES_ROWS_FILE="rows.sql.postgres"
 
 REQUIRED_DEPS=("matrix-synapse" "psycopg2")
 
@@ -22,7 +24,7 @@ usage() {
   echo "  Username to connect to local postgres instance. The password will be requested"
   echo "  during script execution."
   echo "-c"
-  echo "  CI mode. Enables coverage tracking and prints every command that the script runs."
+  echo "  CI mode. Prints every command that the script runs."
   echo "-o <path>"
   echo "  Directory to output full schema files to."
   echo "-h"
@@ -37,11 +39,6 @@ while getopts "p:co:h" opt; do
     c)
       # Print all commands that are being executed
       set -x
-
-      # Modify required dependencies for coverage
-      REQUIRED_DEPS+=("coverage" "coverage-enable-subprocess")
-
-      COVERAGE=1
       ;;
     o)
       command -v realpath > /dev/null || (echo "The -o flag requires the 'realpath' binary to be installed" && exit 1)
@@ -102,6 +99,7 @@ SQLITE_DB=$TMPDIR/homeserver.db
 POSTGRES_CONFIG=$TMPDIR/postgres.conf
 
 # Ensure these files are delete on script exit
+# TODO: the trap should also drop the temp postgres DB
 trap 'rm -rf $TMPDIR' EXIT
 
 cat > "$SQLITE_CONFIG" <<EOF
@@ -147,48 +145,34 @@ python -m synapse.app.homeserver --generate-keys -c "$SQLITE_CONFIG"
 
 # Make sure the SQLite3 database is using the latest schema and has no pending background update.
 echo "Running db background jobs..."
-synapse/_scripts/update_synapse_database.py --database-config --run-background-updates "$SQLITE_CONFIG"
+synapse/_scripts/update_synapse_database.py --database-config "$SQLITE_CONFIG" --run-background-updates
 
 # Create the PostgreSQL database.
 echo "Creating postgres database..."
 createdb --lc-collate=C --lc-ctype=C --template=template0 "$POSTGRES_DB_NAME"
 
-echo "Copying data from SQLite3 to Postgres with synapse_port_db..."
-if [ -z "$COVERAGE" ]; then
-  # No coverage needed
-  synapse/_scripts/synapse_port_db.py --sqlite-database "$SQLITE_DB" --postgres-config "$POSTGRES_CONFIG"
-else
-  # Coverage desired
-  coverage run synapse/_scripts/synapse_port_db.py --sqlite-database "$SQLITE_DB" --postgres-config "$POSTGRES_CONFIG"
-fi
+echo "Running db background jobs..."
+synapse/_scripts/update_synapse_database.py --database-config "$POSTGRES_CONFIG" --run-background-updates
+
 
 # Delete schema_version, applied_schema_deltas and applied_module_schemas tables
 # Also delete any shadow tables from fts4
-# This needs to be done after synapse_port_db is run
 echo "Dropping unwanted db tables..."
 SQL="
 DROP TABLE schema_version;
 DROP TABLE applied_schema_deltas;
 DROP TABLE applied_module_schemas;
-DROP TABLE event_search_content;
-DROP TABLE event_search_segments;
-DROP TABLE event_search_segdir;
-DROP TABLE event_search_docsize;
-DROP TABLE event_search_stat;
-DROP TABLE user_directory_search_content;
-DROP TABLE user_directory_search_segments;
-DROP TABLE user_directory_search_segdir;
-DROP TABLE user_directory_search_docsize;
-DROP TABLE user_directory_search_stat;
 "
 sqlite3 "$SQLITE_DB" <<< "$SQL"
 psql "$POSTGRES_DB_NAME" -w <<< "$SQL"
 
-echo "Dumping SQLite3 schema to '$OUTPUT_DIR/$SQLITE_FULL_SCHEMA_OUTPUT_FILE'..."
-sqlite3 "$SQLITE_DB" ".dump" > "$OUTPUT_DIR/$SQLITE_FULL_SCHEMA_OUTPUT_FILE"
+echo "Dumping SQLite3 schema to '$OUTPUT_DIR/$SQLITE_SCHEMA_FILE' and '$OUTPUT_DIR/$SQLITE_ROWS_FILE'..."
+sqlite3 "$SQLITE_DB" ".schema --indent" > "$OUTPUT_DIR/$SQLITE_SCHEMA_FILE"
+sqlite3 "$SQLITE_DB" ".dump --data-only --nosys" > "$OUTPUT_DIR/$SQLITE_ROWS_FILE"
 
-echo "Dumping Postgres schema to '$OUTPUT_DIR/$POSTGRES_FULL_SCHEMA_OUTPUT_FILE'..."
-pg_dump --format=plain --no-tablespaces --no-acl --no-owner $POSTGRES_DB_NAME | sed -e '/^--/d' -e 's/public\.//g' -e '/^SET /d' -e '/^SELECT /d' > "$OUTPUT_DIR/$POSTGRES_FULL_SCHEMA_OUTPUT_FILE"
+echo "Dumping Postgres schema to '$OUTPUT_DIR/$POSTGRES_SCHEMA_FILE' and '$OUTPUT_DIR/$POSTGRES_ROWS_FILE'..."
+pg_dump --format=plain --schema-only         --no-tablespaces --no-acl --no-owner "$POSTGRES_DB_NAME" | sed -e '/^$/d' -e '/^--/d' -e 's/public\.//g' -e '/^SET /d' -e '/^SELECT /d' > "$OUTPUT_DIR/$POSTGRES_SCHEMA_FILE"
+pg_dump --format=plain --data-only --inserts --no-tablespaces --no-acl --no-owner "$POSTGRES_DB_NAME" | sed -e '/^$/d' -e '/^--/d' -e 's/public\.//g' -e '/^SET /d' -e '/^SELECT /d' > "$OUTPUT_DIR/$POSTGRES_ROWS_FILE"
 
 echo "Cleaning up temporary Postgres database..."
 dropdb $POSTGRES_DB_NAME
diff --git a/scripts-dev/release.py b/scripts-dev/release.py
index 6603bc593b67..c82c58c54b05 100755
--- a/scripts-dev/release.py
+++ b/scripts-dev/release.py
@@ -427,11 +427,12 @@ def _publish(gh_token: str) -> None:
 
 
 @cli.command()
-def upload() -> None:
-    _upload()
+@click.option("--gh-token", envvar=["GH_TOKEN", "GITHUB_TOKEN"], required=False)
+def upload(gh_token: Optional[str]) -> None:
+    _upload(gh_token)
 
 
-def _upload() -> None:
+def _upload(gh_token: Optional[str]) -> None:
     """Upload release to pypi."""
 
     current_version = get_package_version()
@@ -444,18 +445,40 @@ def _upload() -> None:
         click.echo("Tag {tag_name} (tag.commit) is not currently checked out!")
         click.get_current_context().abort()
 
-    pypi_asset_names = [
-        f"matrix_synapse-{current_version}-py3-none-any.whl",
-        f"matrix-synapse-{current_version}.tar.gz",
-    ]
+    # Query all the assets corresponding to this release.
+    gh = Github(gh_token)
+    gh_repo = gh.get_repo("matrix-org/synapse")
+    gh_release = gh_repo.get_release(tag_name)
+
+    all_assets = set(gh_release.get_assets())
+
+    # Only accept the wheels and sdist.
+    # Notably: we don't care about debs.tar.xz.
+    asset_names_and_urls = sorted(
+        (asset.name, asset.browser_download_url)
+        for asset in all_assets
+        if asset.name.endswith((".whl", ".tar.gz"))
+    )
+
+    # Print out what we've determined.
+    print("Found relevant assets:")
+    for asset_name, _ in asset_names_and_urls:
+        print(f" - {asset_name}")
+
+    ignored_asset_names = sorted(
+        {asset.name for asset in all_assets}
+        - {asset_name for asset_name, _ in asset_names_and_urls}
+    )
+    print("\nIgnoring irrelevant assets:")
+    for asset_name in ignored_asset_names:
+        print(f" - {asset_name}")
 
     with TemporaryDirectory(prefix=f"synapse_upload_{tag_name}_") as tmpdir:
-        for name in pypi_asset_names:
+        for name, asset_download_url in asset_names_and_urls:
             filename = path.join(tmpdir, name)
-            url = f"https://github.com/matrix-org/synapse/releases/download/{tag_name}/{name}"
 
             click.echo(f"Downloading {name} into {filename}")
-            urllib.request.urlretrieve(url, filename=filename)
+            urllib.request.urlretrieve(asset_download_url, filename=filename)
 
         if click.confirm("Upload to PyPI?", default=True):
             subprocess.run("twine upload *", shell=True, cwd=tmpdir)
@@ -672,7 +695,7 @@ def full(gh_token: str) -> None:
     _publish(gh_token)
 
     click.echo("\n*** upload ***")
-    _upload()
+    _upload(gh_token)
 
     click.echo("\n*** merge back ***")
     _merge_back()
diff --git a/stubs/synapse/__init__.pyi b/stubs/synapse/__init__.pyi
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/stubs/synapse/synapse_rust.pyi b/stubs/synapse/synapse_rust.pyi
new file mode 100644
index 000000000000..8658d3138f89
--- /dev/null
+++ b/stubs/synapse/synapse_rust.pyi
@@ -0,0 +1,2 @@
+def sum_as_string(a: int, b: int) -> str: ...
+def get_rust_file_digest() -> str: ...
diff --git a/synapse/__init__.py b/synapse/__init__.py
index b1369aca8f72..1bed6393bdb6 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -20,6 +20,8 @@
 import os
 import sys
 
+from synapse.util.rust import check_rust_lib_up_to_date
+
 # Check that we're not running on an unsupported Python version.
 if sys.version_info < (3, 7):
     print("Synapse requires Python 3.7 or above.")
@@ -78,3 +80,6 @@
     from synapse.util.patch_inline_callbacks import do_patch
 
     do_patch()
+
+
+check_rust_lib_up_to_date()
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index a3bfaa90ec86..35a3e2ac27e0 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -32,12 +32,14 @@
 from synapse.http import get_request_user_agent
 from synapse.http.site import SynapseRequest
 from synapse.logging.opentracing import (
+    SynapseTags,
     active_span,
     force_tracing,
     start_active_span,
     trace,
 )
 from synapse.types import Requester, create_requester
+from synapse.util.cancellation import cancellable
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -118,6 +120,7 @@ async def check_user_in_room(
             errcode=Codes.NOT_JOINED,
         )
 
+    @cancellable
     async def get_user_by_req(
         self,
         request: SynapseRequest,
@@ -159,6 +162,12 @@ async def get_user_by_req(
                 parent_span.set_tag(
                     "authenticated_entity", requester.authenticated_entity
                 )
+                # We tag the Synapse instance name so that it's an easy jumping
+                # off point into the logs. Can also be used to filter for an
+                # instance that is under load.
+                parent_span.set_tag(
+                    SynapseTags.INSTANCE_NAME, self.hs.get_instance_name()
+                )
                 parent_span.set_tag("user_id", requester.user.to_string())
                 if requester.device_id is not None:
                     parent_span.set_tag("device_id", requester.device_id)
@@ -166,6 +175,7 @@ async def get_user_by_req(
                     parent_span.set_tag("appservice_id", requester.app_service.id)
             return requester
 
+    @cancellable
     async def _wrapped_get_user_by_req(
         self,
         request: SynapseRequest,
@@ -290,6 +300,7 @@ async def validate_appservice_can_control_user_id(
                 403, "Application service has not registered this user (%s)" % user_id
             )
 
+    @cancellable
     async def _get_appservice_user(self, request: Request) -> Optional[Requester]:
         """
         Given a request, reads the request parameters to determine:
@@ -457,15 +468,6 @@ async def get_user_by_access_token(
             )
             raise InvalidClientTokenError("Invalid access token passed.")
 
-    def get_appservice_by_req(self, request: SynapseRequest) -> ApplicationService:
-        token = self.get_access_token_from_request(request)
-        service = self.store.get_app_service_by_token(token)
-        if not service:
-            logger.warning("Unrecognised appservice access token.")
-            raise InvalidClientTokenError()
-        request.requester = create_requester(service.sender, app_service=service)
-        return service
-
     async def is_server_admin(self, requester: Requester) -> bool:
         """Check if the given user is a local server admin.
 
@@ -532,6 +534,7 @@ def has_access_token(request: Request) -> bool:
         return bool(query_params) or bool(auth_headers)
 
     @staticmethod
+    @cancellable
     def get_access_token_from_request(request: Request) -> str:
         """Extracts the access_token from the request.
 
diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index 102889ac49df..f7f46f8d8008 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -140,13 +140,13 @@
 
 
 @FormatChecker.cls_checks("matrix_room_id")
-def matrix_room_id_validator(room_id_str: str) -> bool:
-    return RoomID.is_valid(room_id_str)
+def matrix_room_id_validator(room_id: object) -> bool:
+    return isinstance(room_id, str) and RoomID.is_valid(room_id)
 
 
 @FormatChecker.cls_checks("matrix_user_id")
-def matrix_user_id_validator(user_id_str: str) -> bool:
-    return UserID.is_valid(user_id_str)
+def matrix_user_id_validator(user_id: object) -> bool:
+    return isinstance(user_id, str) and UserID.is_valid(user_id)
 
 
 class Filtering:
diff --git a/synapse/api/room_versions.py b/synapse/api/room_versions.py
index a0e4ab6db630..e37acb0f1edf 100644
--- a/synapse/api/room_versions.py
+++ b/synapse/api/room_versions.py
@@ -19,18 +19,23 @@
 
 class EventFormatVersions:
     """This is an internal enum for tracking the version of the event format,
-    independently from the room version.
+    independently of the room version.
+
+    To reduce confusion, the event format versions are named after the room
+    versions that they were used or introduced in.
+    The concept of an 'event format version' is specific to Synapse (the
+    specification does not mention this term.)
     """
 
-    V1 = 1  # $id:server event id format
-    V2 = 2  # MSC1659-style $hash event id format: introduced for room v3
-    V3 = 3  # MSC1884-style $hash format: introduced for room v4
+    ROOM_V1_V2 = 1  # $id:server event id format: used for room v1 and v2
+    ROOM_V3 = 2  # MSC1659-style $hash event id format: used for room v3
+    ROOM_V4_PLUS = 3  # MSC1884-style $hash format: introduced for room v4
 
 
 KNOWN_EVENT_FORMAT_VERSIONS = {
-    EventFormatVersions.V1,
-    EventFormatVersions.V2,
-    EventFormatVersions.V3,
+    EventFormatVersions.ROOM_V1_V2,
+    EventFormatVersions.ROOM_V3,
+    EventFormatVersions.ROOM_V4_PLUS,
 }
 
 
@@ -92,7 +97,7 @@ class RoomVersions:
     V1 = RoomVersion(
         "1",
         RoomDisposition.STABLE,
-        EventFormatVersions.V1,
+        EventFormatVersions.ROOM_V1_V2,
         StateResolutionVersions.V1,
         enforce_key_validity=False,
         special_case_aliases_auth=True,
@@ -110,7 +115,7 @@ class RoomVersions:
     V2 = RoomVersion(
         "2",
         RoomDisposition.STABLE,
-        EventFormatVersions.V1,
+        EventFormatVersions.ROOM_V1_V2,
         StateResolutionVersions.V2,
         enforce_key_validity=False,
         special_case_aliases_auth=True,
@@ -128,7 +133,7 @@ class RoomVersions:
     V3 = RoomVersion(
         "3",
         RoomDisposition.STABLE,
-        EventFormatVersions.V2,
+        EventFormatVersions.ROOM_V3,
         StateResolutionVersions.V2,
         enforce_key_validity=False,
         special_case_aliases_auth=True,
@@ -146,7 +151,7 @@ class RoomVersions:
     V4 = RoomVersion(
         "4",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=False,
         special_case_aliases_auth=True,
@@ -164,7 +169,7 @@ class RoomVersions:
     V5 = RoomVersion(
         "5",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=True,
@@ -182,7 +187,7 @@ class RoomVersions:
     V6 = RoomVersion(
         "6",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -200,7 +205,7 @@ class RoomVersions:
     MSC2176 = RoomVersion(
         "org.matrix.msc2176",
         RoomDisposition.UNSTABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -218,7 +223,7 @@ class RoomVersions:
     V7 = RoomVersion(
         "7",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -236,7 +241,7 @@ class RoomVersions:
     V8 = RoomVersion(
         "8",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -254,7 +259,7 @@ class RoomVersions:
     V9 = RoomVersion(
         "9",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -272,7 +277,7 @@ class RoomVersions:
     MSC3787 = RoomVersion(
         "org.matrix.msc3787",
         RoomDisposition.UNSTABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -290,7 +295,7 @@ class RoomVersions:
     V10 = RoomVersion(
         "10",
         RoomDisposition.STABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
@@ -308,7 +313,7 @@ class RoomVersions:
     MSC2716v4 = RoomVersion(
         "org.matrix.msc2716v4",
         RoomDisposition.UNSTABLE,
-        EventFormatVersions.V3,
+        EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
diff --git a/synapse/app/phone_stats_home.py b/synapse/app/phone_stats_home.py
index 51c8d1571112..53db1e85b3d8 100644
--- a/synapse/app/phone_stats_home.py
+++ b/synapse/app/phone_stats_home.py
@@ -32,15 +32,15 @@
 _stats_process: List[Tuple[int, "resource.struct_rusage"]] = []
 
 # Gauges to expose monthly active user control metrics
-current_mau_gauge = Gauge("synapse_admin_mau:current", "Current MAU")
+current_mau_gauge = Gauge("synapse_admin_mau_current", "Current MAU")
 current_mau_by_service_gauge = Gauge(
     "synapse_admin_mau_current_mau_by_service",
     "Current MAU by service",
     ["app_service"],
 )
-max_mau_gauge = Gauge("synapse_admin_mau:max", "MAU Limit")
+max_mau_gauge = Gauge("synapse_admin_mau_max", "MAU Limit")
 registered_reserved_users_mau_gauge = Gauge(
-    "synapse_admin_mau:registered_reserved_users",
+    "synapse_admin_mau_registered_reserved_users",
     "Registered users with reserved threepids",
 )
 
diff --git a/synapse/config/key.py b/synapse/config/key.py
index cc75efdf8fc2..f3dc4df69540 100644
--- a/synapse/config/key.py
+++ b/synapse/config/key.py
@@ -217,7 +217,18 @@ def read_signing_keys(self, signing_key_path: str, name: str) -> List[SigningKey
 
         signing_keys = self.read_file(signing_key_path, name)
         try:
-            return read_signing_keys(signing_keys.splitlines(True))
+            loaded_signing_keys = read_signing_keys(
+                [
+                    signing_key_line
+                    for signing_key_line in signing_keys.splitlines(keepends=False)
+                    if signing_key_line.strip()
+                ]
+            )
+
+            if not loaded_signing_keys:
+                raise ConfigError(f"No signing keys in file {signing_key_path}")
+
+            return loaded_signing_keys
         except Exception as e:
             raise ConfigError("Error reading %s: %s" % (name, str(e)))
 
diff --git a/synapse/config/server.py b/synapse/config/server.py
index c91df636d9a7..f2353ce5fb0a 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -206,6 +206,7 @@ class HttpListenerConfig:
     resources: List[HttpResourceConfig] = attr.Factory(list)
     additional_resources: Dict[str, dict] = attr.Factory(dict)
     tag: Optional[str] = None
+    request_id_header: Optional[str] = None
 
 
 @attr.s(slots=True, frozen=True, auto_attribs=True)
@@ -520,9 +521,11 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
         ):
             raise ConfigError("allowed_avatar_mimetypes must be a list")
 
-        self.listeners = [
-            parse_listener_def(i, x) for i, x in enumerate(config.get("listeners", []))
-        ]
+        listeners = config.get("listeners", [])
+        if not isinstance(listeners, list):
+            raise ConfigError("Expected a list", ("listeners",))
+
+        self.listeners = [parse_listener_def(i, x) for i, x in enumerate(listeners)]
 
         # no_tls is not really supported any more, but let's grandfather it in
         # here.
@@ -889,6 +892,9 @@ def read_gc_thresholds(
 
 def parse_listener_def(num: int, listener: Any) -> ListenerConfig:
     """parse a listener config from the config file"""
+    if not isinstance(listener, dict):
+        raise ConfigError("Expected a dictionary", ("listeners", str(num)))
+
     listener_type = listener["type"]
     # Raise a helpful error if direct TCP replication is still configured.
     if listener_type == "replication":
@@ -928,6 +934,7 @@ def parse_listener_def(num: int, listener: Any) -> ListenerConfig:
             resources=resources,
             additional_resources=listener.get("additional_resources", {}),
             tag=listener.get("tag"),
+            request_id_header=listener.get("request_id_header"),
         )
 
     return ListenerConfig(port, bind_addresses, listener_type, tls, http_config)
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index 389b0c5d533d..c7d5ef92fc00 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -109,7 +109,7 @@ def validate_event_for_room_version(event: "EventBase") -> None:
         if not is_invite_via_3pid:
             raise AuthError(403, "Event not signed by sender's server")
 
-    if event.format_version in (EventFormatVersions.V1,):
+    if event.format_version in (EventFormatVersions.ROOM_V1_V2,):
         # Only older room versions have event IDs to check.
         event_id_domain = get_domain_from_id(event.event_id)
 
@@ -716,7 +716,7 @@ def check_redaction(
     if user_level >= redact_level:
         return False
 
-    if room_version_obj.event_format == EventFormatVersions.V1:
+    if room_version_obj.event_format == EventFormatVersions.ROOM_V1_V2:
         redacter_domain = get_domain_from_id(event.event_id)
         if not isinstance(event.redacts, str):
             return False
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index 39ad2793d98d..b2c9119fd0fb 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -442,7 +442,7 @@ def __repr__(self) -> str:
 
 
 class FrozenEvent(EventBase):
-    format_version = EventFormatVersions.V1  # All events of this type are V1
+    format_version = EventFormatVersions.ROOM_V1_V2  # All events of this type are V1
 
     def __init__(
         self,
@@ -490,7 +490,7 @@ def event_id(self) -> str:
 
 
 class FrozenEventV2(EventBase):
-    format_version = EventFormatVersions.V2  # All events of this type are V2
+    format_version = EventFormatVersions.ROOM_V3  # All events of this type are V2
 
     def __init__(
         self,
@@ -567,7 +567,7 @@ def auth_event_ids(self) -> Sequence[str]:
 class FrozenEventV3(FrozenEventV2):
     """FrozenEventV3, which differs from FrozenEventV2 only in the event_id format"""
 
-    format_version = EventFormatVersions.V3  # All events of this type are V3
+    format_version = EventFormatVersions.ROOM_V4_PLUS  # All events of this type are V3
 
     @property
     def event_id(self) -> str:
@@ -597,11 +597,11 @@ def _event_type_from_format_version(
         `FrozenEvent`
     """
 
-    if format_version == EventFormatVersions.V1:
+    if format_version == EventFormatVersions.ROOM_V1_V2:
         return FrozenEvent
-    elif format_version == EventFormatVersions.V2:
+    elif format_version == EventFormatVersions.ROOM_V3:
         return FrozenEventV2
-    elif format_version == EventFormatVersions.V3:
+    elif format_version == EventFormatVersions.ROOM_V4_PLUS:
         return FrozenEventV3
     else:
         raise Exception("No event format %r" % (format_version,))
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 17f624b68f58..e2ee10dd3ddc 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -137,7 +137,7 @@ async def build(
         # The types of auth/prev events changes between event versions.
         prev_events: Union[List[str], List[Tuple[str, Dict[str, str]]]]
         auth_events: Union[List[str], List[Tuple[str, Dict[str, str]]]]
-        if format_version == EventFormatVersions.V1:
+        if format_version == EventFormatVersions.ROOM_V1_V2:
             auth_events = await self._store.add_event_hashes(auth_event_ids)
             prev_events = await self._store.add_event_hashes(prev_event_ids)
         else:
@@ -167,7 +167,6 @@ async def build(
             "content": self.content,
             "unsigned": self.unsigned,
             "depth": depth,
-            "prev_state": [],
         }
 
         if self.is_state():
@@ -253,7 +252,7 @@ def create_local_event_from_event_dict(
 
     time_now = int(clock.time_msec())
 
-    if format_version == EventFormatVersions.V1:
+    if format_version == EventFormatVersions.ROOM_V1_V2:
         event_dict["event_id"] = _create_event_id(clock, hostname)
 
     event_dict["origin"] = hostname
diff --git a/synapse/events/validator.py b/synapse/events/validator.py
index 71c87ef4f63d..01a11926f6e8 100644
--- a/synapse/events/validator.py
+++ b/synapse/events/validator.py
@@ -45,7 +45,7 @@ def validate_new(self, event: EventBase, config: HomeServerConfig) -> None:
         """
         self.validate_builder(event)
 
-        if event.format_version == EventFormatVersions.V1:
+        if event.format_version == EventFormatVersions.ROOM_V1_V2:
             EventID.from_string(event.event_id)
 
         required = [
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index 4269a98db2db..abe2c1971a19 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -194,7 +194,7 @@ async def _check_sigs_on_pdu(
     # event id's domain (normally only the case for joins/leaves), and add additional
     # checks. Only do this if the room version has a concept of event ID domain
     # (ie, the room version uses old-style non-hash event IDs).
-    if room_version.event_format == EventFormatVersions.V1:
+    if room_version.event_format == EventFormatVersions.ROOM_V1_V2:
         event_domain = get_domain_from_id(pdu.event_id)
         if event_domain != sender_domain:
             try:
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 7ee2974bb155..464672a3da81 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -906,9 +906,6 @@ async def send_request(destination: str) -> Tuple[str, EventBase, RoomVersion]:
             # The protoevent received over the JSON wire may not have all
             # the required fields. Lets just gloss over that because
             # there's some we never care about
-            if "prev_state" not in pdu_dict:
-                pdu_dict["prev_state"] = []
-
             ev = builder.create_local_event_from_event_dict(
                 self._clock,
                 self.hostname,
@@ -1190,7 +1187,7 @@ async def _do_send_invite(
             # Otherwise, consider it a legitimate error and raise.
             err = e.to_synapse_error()
             if self._is_unknown_endpoint(e, err):
-                if room_version.event_format != EventFormatVersions.V1:
+                if room_version.event_format != EventFormatVersions.ROOM_V1_V2:
                     raise SynapseError(
                         400,
                         "User's homeserver does not support this room version",
diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index ac467ebc2f43..a000b5399951 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -62,12 +62,12 @@
 logger = logging.getLogger(__name__)
 
 sent_pdus_destination_dist_count = Counter(
-    "synapse_federation_client_sent_pdu_destinations:count",
+    "synapse_federation_client_sent_pdu_destinations_count",
     "Number of PDUs queued for sending to one or more destinations",
 )
 
 sent_pdus_destination_dist_total = Counter(
-    "synapse_federation_client_sent_pdu_destinations:total",
+    "synapse_federation_client_sent_pdu_destinations",
     "Total number of PDUs queued for sending across all destinations",
 )
 
diff --git a/synapse/federation/transport/server/federation.py b/synapse/federation/transport/server/federation.py
index f7884bfbe045..6bb4659c4c9e 100644
--- a/synapse/federation/transport/server/federation.py
+++ b/synapse/federation/transport/server/federation.py
@@ -549,8 +549,7 @@ async def on_POST(
 
 
 class FederationGetMissingEventsServlet(BaseFederationServerServlet):
-    # TODO(paul): Why does this path alone end with "/?" optional?
-    PATH = "/get_missing_events/(?P<room_id>[^/]*)/?"
+    PATH = "/get_missing_events/(?P<room_id>[^/]*)"
 
     async def on_POST(
         self,
diff --git a/synapse/handlers/admin.py b/synapse/handlers/admin.py
index d4fe7df533a1..cf9f19608af1 100644
--- a/synapse/handlers/admin.py
+++ b/synapse/handlers/admin.py
@@ -70,6 +70,7 @@ async def get_user(self, user: UserID) -> Optional[JsonDict]:
             "appservice_id",
             "consent_server_notice_sent",
             "consent_version",
+            "consent_ts",
             "user_type",
             "is_guest",
         }
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 9c2c3a0e687c..901e2310b706 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -45,13 +45,13 @@
     JsonDict,
     StreamKeyType,
     StreamToken,
-    UserID,
     get_domain_from_id,
     get_verify_key_from_cross_signing_key,
 )
 from synapse.util import stringutils
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.cancellation import cancellable
 from synapse.util.metrics import measure_func
 from synapse.util.retryutils import NotRetryingDestination
 
@@ -124,6 +124,7 @@ async def get_device(self, user_id: str, device_id: str) -> JsonDict:
 
         return device
 
+    @cancellable
     async def get_device_changes_in_shared_rooms(
         self, user_id: str, room_ids: Collection[str], from_token: StreamToken
     ) -> Collection[str]:
@@ -163,6 +164,7 @@ async def get_device_changes_in_shared_rooms(
 
     @trace
     @measure_func("device.get_user_ids_changed")
+    @cancellable
     async def get_user_ids_changed(
         self, user_id: str, from_token: StreamToken
     ) -> JsonDict:
@@ -321,8 +323,6 @@ def __init__(self, hs: "HomeServer"):
             self.device_list_updater.incoming_device_list_update,
         )
 
-        hs.get_distributor().observe("user_left_room", self.user_left_room)
-
         # Whether `_handle_new_device_update_async` is currently processing.
         self._handle_new_device_update_is_processing = False
 
@@ -566,14 +566,6 @@ async def notify_user_signature_update(
             StreamKeyType.DEVICE_LIST, position, users=[from_user_id]
         )
 
-    async def user_left_room(self, user: UserID, room_id: str) -> None:
-        user_id = user.to_string()
-        room_ids = await self.store.get_rooms_for_user(user_id)
-        if not room_ids:
-            # We no longer share rooms with this user, so we'll no longer
-            # receive device updates. Mark this in DB.
-            await self.store.mark_remote_user_device_list_as_unsubscribed(user_id)
-
     async def store_dehydrated_device(
         self,
         user_id: str,
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index c938339ddd89..09a2492afc9e 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -37,7 +37,8 @@
     get_verify_key_from_cross_signing_key,
 )
 from synapse.util import json_decoder, unwrapFirstError
-from synapse.util.async_helpers import Linearizer
+from synapse.util.async_helpers import Linearizer, delay_cancellation
+from synapse.util.cancellation import cancellable
 from synapse.util.retryutils import NotRetryingDestination
 
 if TYPE_CHECKING:
@@ -91,6 +92,7 @@ def __init__(self, hs: "HomeServer"):
         )
 
     @trace
+    @cancellable
     async def query_devices(
         self,
         query_body: JsonDict,
@@ -173,6 +175,35 @@ async def query_devices(
                     user_ids_not_in_cache,
                     remote_results,
                 ) = await self.store.get_user_devices_from_cache(query_list)
+
+                # Check that the homeserver still shares a room with all cached users.
+                # Note that this check may be slightly racy when a remote user leaves a
+                # room after we have fetched their cached device list. In the worst case
+                # we will do extra federation queries for devices that we had cached.
+                cached_users = set(remote_results.keys())
+                valid_cached_users = (
+                    await self.store.get_users_server_still_shares_room_with(
+                        remote_results.keys()
+                    )
+                )
+                invalid_cached_users = cached_users - valid_cached_users
+                if invalid_cached_users:
+                    # Fix up results. If we get here, it means there was either a bug in
+                    # device list tracking, or we hit the race mentioned above.
+                    # TODO: In practice, this path is hit fairly often in existing
+                    #       deployments when clients query the keys of departed remote
+                    #       users. A background update to mark the appropriate device
+                    #       lists as unsubscribed is needed.
+                    #       https://github.com/matrix-org/synapse/issues/13651
+                    # Note that this currently introduces a failure mode when clients
+                    # are trying to decrypt old messages from a remote user whose
+                    # homeserver is no longer available. We may want to consider falling
+                    # back to the cached data when we fail to retrieve a device list
+                    # over federation for such remote users.
+                    user_ids_not_in_cache.update(invalid_cached_users)
+                    for invalid_user_id in invalid_cached_users:
+                        remote_results.pop(invalid_user_id)
+
                 for user_id, devices in remote_results.items():
                     user_devices = results.setdefault(user_id, {})
                     for device_id, device in devices.items():
@@ -208,22 +239,26 @@ async def query_devices(
                     r[user_id] = remote_queries[user_id]
 
             # Now fetch any devices that we don't have in our cache
+            # TODO It might make sense to propagate cancellations into the
+            #      deferreds which are querying remote homeservers.
             await make_deferred_yieldable(
-                defer.gatherResults(
-                    [
-                        run_in_background(
-                            self._query_devices_for_destination,
-                            results,
-                            cross_signing_keys,
-                            failures,
-                            destination,
-                            queries,
-                            timeout,
-                        )
-                        for destination, queries in remote_queries_not_in_cache.items()
-                    ],
-                    consumeErrors=True,
-                ).addErrback(unwrapFirstError)
+                delay_cancellation(
+                    defer.gatherResults(
+                        [
+                            run_in_background(
+                                self._query_devices_for_destination,
+                                results,
+                                cross_signing_keys,
+                                failures,
+                                destination,
+                                queries,
+                                timeout,
+                            )
+                            for destination, queries in remote_queries_not_in_cache.items()
+                        ],
+                        consumeErrors=True,
+                    ).addErrback(unwrapFirstError)
+                )
             )
 
             ret = {"device_keys": results, "failures": failures}
@@ -347,6 +382,7 @@ async def _query_devices_for_destination(
 
         return
 
+    @cancellable
     async def get_cross_signing_keys_from_cache(
         self, query: Iterable[str], from_user_id: Optional[str]
     ) -> Dict[str, Dict[str, dict]]:
@@ -393,6 +429,7 @@ async def get_cross_signing_keys_from_cache(
         }
 
     @trace
+    @cancellable
     async def query_local_devices(
         self, query: Mapping[str, Optional[List[str]]]
     ) -> Dict[str, Dict[str, dict]]:
diff --git a/synapse/handlers/federation_event.py b/synapse/handlers/federation_event.py
index ace7adcffb61..efcdb8405783 100644
--- a/synapse/handlers/federation_event.py
+++ b/synapse/handlers/federation_event.py
@@ -862,7 +862,15 @@ async def _process_pulled_event(
             self._sanity_check_event(event)
         except SynapseError as err:
             logger.warning("Event %s failed sanity check: %s", event_id, err)
+            await self._store.record_event_failed_pull_attempt(
+                event.room_id, event_id, str(err)
+            )
             return
+        except Exception as exc:
+            await self._store.record_event_failed_pull_attempt(
+                event.room_id, event_id, str(exc)
+            )
+            raise exc
 
         try:
             try:
@@ -897,10 +905,19 @@ async def _process_pulled_event(
                     backfilled=backfilled,
                 )
         except FederationError as e:
+            await self._store.record_event_failed_pull_attempt(
+                event.room_id, event_id, str(e)
+            )
+
             if e.code == 403:
                 logger.warning("Pulled event %s failed history check.", event_id)
             else:
                 raise
+        except Exception as exc:
+            await self._store.record_event_failed_pull_attempt(
+                event.room_id, event_id, str(exc)
+            )
+            raise exc
 
     @trace
     async def _compute_event_context_with_maybe_missing_prevs(
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index efe191fb4ebb..ca8815c481c3 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -754,20 +754,12 @@ async def _is_exempt_from_privacy_policy(
         if builder.type == EventTypes.Member:
             membership = builder.content.get("membership", None)
             if membership == Membership.JOIN:
-                return await self._is_server_notices_room(builder.room_id)
+                return await self.store.is_server_notice_room(builder.room_id)
             elif membership == Membership.LEAVE:
                 # the user is always allowed to leave (but not kick people)
                 return builder.state_key == requester.user.to_string()
         return False
 
-    async def _is_server_notices_room(self, room_id: str) -> bool:
-        if self.config.servernotices.server_notices_mxid is None:
-            return False
-        is_server_notices_room = await self.store.check_local_user_in_room(
-            user_id=self.config.servernotices.server_notices_mxid, room_id=room_id
-        )
-        return is_server_notices_room
-
     async def assert_accepted_privacy_policy(self, requester: Requester) -> None:
         """Check if a user has accepted the privacy policy
 
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index 83adabda96ed..e17176fbbeb2 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -28,6 +28,7 @@
 from synapse.handlers.room import ShutdownRoomResponse
 from synapse.logging.opentracing import trace
 from synapse.metrics.background_process_metrics import run_as_background_process
+from synapse.rest.admin._base import assert_user_is_admin
 from synapse.storage.state import StateFilter
 from synapse.streams.config import PaginationConfig
 from synapse.types import JsonDict, Requester, StreamKeyType
@@ -435,6 +436,7 @@ async def get_messages(
         pagin_config: PaginationConfig,
         as_client_event: bool = True,
         event_filter: Optional[Filter] = None,
+        use_admin_priviledge: bool = False,
     ) -> JsonDict:
         """Get messages in a room.
 
@@ -444,10 +446,16 @@ async def get_messages(
             pagin_config: The pagination config rules to apply, if any.
             as_client_event: True to get events in client-server format.
             event_filter: Filter to apply to results or None
+            use_admin_priviledge: if `True`, return all events, regardless
+                of whether `user` has access to them. To be used **ONLY**
+                from the admin API.
 
         Returns:
             Pagination API results
         """
+        if use_admin_priviledge:
+            await assert_user_is_admin(self.auth, requester)
+
         user_id = requester.user.to_string()
 
         if pagin_config.from_token:
@@ -470,12 +478,14 @@ async def get_messages(
         room_token = from_token.room_key
 
         async with self.pagination_lock.read(room_id):
-            (
-                membership,
-                member_event_id,
-            ) = await self.auth.check_user_in_room_or_world_readable(
-                room_id, requester, allow_departed_users=True
-            )
+            (membership, member_event_id) = (None, None)
+            if not use_admin_priviledge:
+                (
+                    membership,
+                    member_event_id,
+                ) = await self.auth.check_user_in_room_or_world_readable(
+                    room_id, requester, allow_departed_users=True
+                )
 
             if pagin_config.direction == "b":
                 # if we're going backwards, we might need to backfill. This
@@ -487,7 +497,7 @@ async def get_messages(
                         room_id, room_token.stream
                     )
 
-                if membership == Membership.LEAVE:
+                if not use_admin_priviledge and membership == Membership.LEAVE:
                     # If they have left the room then clamp the token to be before
                     # they left the room, to save the effort of loading from the
                     # database.
@@ -540,12 +550,13 @@ async def get_messages(
         if event_filter:
             events = await event_filter.filter(events)
 
-        events = await filter_events_for_client(
-            self._storage_controllers,
-            user_id,
-            events,
-            is_peeking=(member_event_id is None),
-        )
+        if not use_admin_priviledge:
+            events = await filter_events_for_client(
+                self._storage_controllers,
+                user_id,
+                events,
+                is_peeking=(member_event_id is None),
+            )
 
         # if after the filter applied there are no more events
         # return immediately - but there might be more in next_token batch
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 5d4adf5bfd74..8d01f4bf2be5 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -837,7 +837,7 @@ async def update_membership_locked(
                 old_membership == Membership.INVITE
                 and effective_membership_state == Membership.LEAVE
             ):
-                is_blocked = await self._is_server_notice_room(room_id)
+                is_blocked = await self.store.is_server_notice_room(room_id)
                 if is_blocked:
                     raise SynapseError(
                         HTTPStatus.FORBIDDEN,
@@ -1617,14 +1617,6 @@ async def _is_host_in_room(self, current_state_ids: StateMap[str]) -> bool:
 
         return False
 
-    async def _is_server_notice_room(self, room_id: str) -> bool:
-        if self._server_notices_mxid is None:
-            return False
-        is_server_notices_room = await self.store.check_local_user_in_room(
-            user_id=self._server_notices_mxid, room_id=room_id
-        )
-        return is_server_notices_room
-
 
 class RoomMemberMasterHandler(RoomMemberHandler):
     def __init__(self, hs: "HomeServer"):
diff --git a/synapse/handlers/room_summary.py b/synapse/handlers/room_summary.py
index 732b0310bcd6..ebd445adcaf3 100644
--- a/synapse/handlers/room_summary.py
+++ b/synapse/handlers/room_summary.py
@@ -453,7 +453,6 @@ async def _summarize_local_room(
                 "type": e.type,
                 "state_key": e.state_key,
                 "content": e.content,
-                "room_id": e.room_id,
                 "sender": e.sender,
                 "origin_server_ts": e.origin_server_ts,
             }
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index af1458b33b64..5f39b79b58a9 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -15,6 +15,7 @@
 import logging
 from typing import (
     TYPE_CHECKING,
+    AbstractSet,
     Any,
     Collection,
     Dict,
@@ -1426,10 +1427,10 @@ async def generate_sync_result(
     async def _generate_sync_entry_for_device_list(
         self,
         sync_result_builder: "SyncResultBuilder",
-        newly_joined_rooms: Set[str],
-        newly_joined_or_invited_or_knocked_users: Set[str],
-        newly_left_rooms: Set[str],
-        newly_left_users: Set[str],
+        newly_joined_rooms: AbstractSet[str],
+        newly_joined_or_invited_or_knocked_users: AbstractSet[str],
+        newly_left_rooms: AbstractSet[str],
+        newly_left_users: AbstractSet[str],
     ) -> DeviceListUpdates:
         """Generate the DeviceListUpdates section of sync
 
@@ -1447,8 +1448,7 @@ async def _generate_sync_entry_for_device_list(
         user_id = sync_result_builder.sync_config.user.to_string()
         since_token = sync_result_builder.since_token
 
-        # We're going to mutate these fields, so lets copy them rather than
-        # assume they won't get used later.
+        # Take a copy since these fields will be mutated later.
         newly_joined_or_invited_or_knocked_users = set(
             newly_joined_or_invited_or_knocked_users
         )
@@ -1648,8 +1648,8 @@ async def _generate_sync_entry_for_account_data(
     async def _generate_sync_entry_for_presence(
         self,
         sync_result_builder: "SyncResultBuilder",
-        newly_joined_rooms: Set[str],
-        newly_joined_or_invited_users: Set[str],
+        newly_joined_rooms: AbstractSet[str],
+        newly_joined_or_invited_users: AbstractSet[str],
     ) -> None:
         """Generates the presence portion of the sync response. Populates the
         `sync_result_builder` with the result.
@@ -1707,7 +1707,7 @@ async def _generate_sync_entry_for_rooms(
         self,
         sync_result_builder: "SyncResultBuilder",
         account_data_by_room: Dict[str, Dict[str, JsonDict]],
-    ) -> Tuple[Set[str], Set[str], Set[str], Set[str]]:
+    ) -> Tuple[AbstractSet[str], AbstractSet[str], AbstractSet[str], AbstractSet[str]]:
         """Generates the rooms portion of the sync response. Populates the
         `sync_result_builder` with the result.
 
@@ -2547,7 +2547,7 @@ class SyncResultBuilder:
     archived: List[ArchivedSyncResult] = attr.Factory(list)
     to_device: List[JsonDict] = attr.Factory(list)
 
-    def calculate_user_changes(self) -> Tuple[Set[str], Set[str]]:
+    def calculate_user_changes(self) -> Tuple[AbstractSet[str], AbstractSet[str]]:
         """Work out which other users have joined or left rooms we are joined to.
 
         This data only is only useful for an incremental sync.
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index 26aaabfb34fa..80acbdcf3ce7 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -28,7 +28,8 @@
     overload,
 )
 
-from pydantic import BaseModel, ValidationError
+from pydantic import BaseModel, MissingError, PydanticValueError, ValidationError
+from pydantic.error_wrappers import ErrorWrapper
 from typing_extensions import Literal
 
 from twisted.web.server import Request
@@ -714,7 +715,21 @@ def parse_and_validate_json_object_from_request(
     try:
         instance = model_type.parse_obj(content)
     except ValidationError as e:
-        raise SynapseError(HTTPStatus.BAD_REQUEST, str(e), errcode=Codes.BAD_JSON)
+        # Choose a matrix error code. The catch-all is BAD_JSON, but we try to find a
+        # more specific error if possible (which occasionally helps us to be spec-
+        # compliant) This is a bit awkward because the spec's error codes aren't very
+        # clear-cut: BAD_JSON arguably overlaps with MISSING_PARAM and INVALID_PARAM.
+        errcode = Codes.BAD_JSON
+
+        raw_errors = e.raw_errors
+        if len(raw_errors) == 1 and isinstance(raw_errors[0], ErrorWrapper):
+            raw_error = raw_errors[0].exc
+            if isinstance(raw_error, MissingError):
+                errcode = Codes.MISSING_PARAM
+            elif isinstance(raw_error, PydanticValueError):
+                errcode = Codes.INVALID_PARAM
+
+        raise SynapseError(HTTPStatus.BAD_REQUEST, str(e), errcode=errcode)
 
     return instance
 
diff --git a/synapse/http/site.py b/synapse/http/site.py
index 4f4f75303807..36bad540e2bf 100644
--- a/synapse/http/site.py
+++ b/synapse/http/site.py
@@ -72,10 +72,12 @@ def __init__(
         site: "SynapseSite",
         *args: Any,
         max_request_body_size: int = 1024,
+        request_id_header: Optional[str] = None,
         **kw: Any,
     ):
         super().__init__(channel, *args, **kw)
         self._max_request_body_size = max_request_body_size
+        self.request_id_header = request_id_header
         self.synapse_site = site
         self.reactor = site.reactor
         self._channel = channel  # this is used by the tests
@@ -172,7 +174,14 @@ def set_opentracing_span(self, span: "opentracing.Span") -> None:
         self._opentracing_span = span
 
     def get_request_id(self) -> str:
-        return "%s-%i" % (self.get_method(), self.request_seq)
+        request_id_value = None
+        if self.request_id_header:
+            request_id_value = self.getHeader(self.request_id_header)
+
+        if request_id_value is None:
+            request_id_value = str(self.request_seq)
+
+        return "%s-%s" % (self.get_method(), request_id_value)
 
     def get_redacted_uri(self) -> str:
         """Gets the redacted URI associated with the request (or placeholder if the URI
@@ -612,12 +621,15 @@ def __init__(
         proxied = config.http_options.x_forwarded
         request_class = XForwardedForRequest if proxied else SynapseRequest
 
+        request_id_header = config.http_options.request_id_header
+
         def request_factory(channel: HTTPChannel, queued: bool) -> Request:
             return request_class(
                 channel,
                 self,
                 max_request_body_size=max_request_body_size,
                 queued=queued,
+                request_id_header=request_id_header,
             )
 
         self.requestFactory = request_factory  # type: ignore
diff --git a/synapse/logging/opentracing.py b/synapse/logging/opentracing.py
index 482316a1ff90..ca2735dd6dc0 100644
--- a/synapse/logging/opentracing.py
+++ b/synapse/logging/opentracing.py
@@ -203,6 +203,9 @@ def set_fates(clotho, lachesis, atropos, father="Zues", mother="Themis"):
 
 # Helper class
 
+# Matches the number suffix in an instance name like "matrix.org client_reader-8"
+STRIP_INSTANCE_NUMBER_SUFFIX_REGEX = re.compile(r"[_-]?\d+$")
+
 
 class _DummyTagNames:
     """wrapper of opentracings tags. We need to have them if we
@@ -295,6 +298,8 @@ class SynapseTags:
     # Whether the sync response has new data to be returned to the client.
     SYNC_RESULT = "sync.new_data"
 
+    INSTANCE_NAME = "instance_name"
+
     # incoming HTTP request ID  (as written in the logs)
     REQUEST_ID = "request_id"
 
@@ -441,9 +446,17 @@ def init_tracer(hs: "HomeServer") -> None:
 
     from jaeger_client.metrics.prometheus import PrometheusMetricsFactory
 
+    # Instance names are opaque strings but by stripping off the number suffix,
+    # we can get something that looks like a "worker type", e.g.
+    # "client_reader-1" -> "client_reader" so we don't spread the traces across
+    # so many services.
+    instance_name_by_type = re.sub(
+        STRIP_INSTANCE_NUMBER_SUFFIX_REGEX, "", hs.get_instance_name()
+    )
+
     config = JaegerConfig(
         config=hs.config.tracing.jaeger_config,
-        service_name=f"{hs.config.server.server_name} {hs.get_instance_name()}",
+        service_name=f"{hs.config.server.server_name} {instance_name_by_type}",
         scope_manager=LogContextScopeManager(),
         metrics_factory=PrometheusMetricsFactory(),
     )
@@ -1032,11 +1045,11 @@ def trace_servlet(
             # with JsonResource).
             scope.span.set_operation_name(request.request_metrics.name)
 
-            # set the tags *after* the servlet completes, in case it decided to
-            # prioritise the span (tags will get dropped on unprioritised spans)
             request_tags[
                 SynapseTags.REQUEST_TAG
             ] = request.request_metrics.start_context.tag
 
+            # set the tags *after* the servlet completes, in case it decided to
+            # prioritise the span (tags will get dropped on unprioritised spans)
             for k, v in request_tags.items():
                 scope.span.set_tag(k, v)
diff --git a/synapse/metrics/_legacy_exposition.py b/synapse/metrics/_legacy_exposition.py
index ff640a49aff8..563d8cc2c60d 100644
--- a/synapse/metrics/_legacy_exposition.py
+++ b/synapse/metrics/_legacy_exposition.py
@@ -34,8 +34,6 @@
 from twisted.web.resource import Resource
 from twisted.web.server import Request
 
-from synapse.util import caches
-
 CONTENT_TYPE_LATEST = "text/plain; version=0.0.4; charset=utf-8"
 
 
@@ -88,11 +86,16 @@ def sample_line(line: Sample, name: str) -> str:
     "synapse_util_caches_cache_hits": "synapse_util_caches_cache:hits",
     "synapse_util_caches_cache_size": "synapse_util_caches_cache:size",
     "synapse_util_caches_cache_evicted_size": "synapse_util_caches_cache:evicted_size",
-    "synapse_util_caches_cache_total": "synapse_util_caches_cache:total",
+    "synapse_util_caches_cache": "synapse_util_caches_cache:total",
     "synapse_util_caches_response_cache_size": "synapse_util_caches_response_cache:size",
     "synapse_util_caches_response_cache_hits": "synapse_util_caches_response_cache:hits",
     "synapse_util_caches_response_cache_evicted_size": "synapse_util_caches_response_cache:evicted_size",
-    "synapse_util_caches_response_cache_total": "synapse_util_caches_response_cache:total",
+    "synapse_util_caches_response_cache": "synapse_util_caches_response_cache:total",
+    "synapse_federation_client_sent_pdu_destinations": "synapse_federation_client_sent_pdu_destinations:total",
+    "synapse_federation_client_sent_pdu_destinations_count": "synapse_federation_client_sent_pdu_destinations:count",
+    "synapse_admin_mau_current": "synapse_admin_mau:current",
+    "synapse_admin_mau_max": "synapse_admin_mau:max",
+    "synapse_admin_mau_registered_reserved_users": "synapse_admin_mau:registered_reserved_users",
 }
 
 
@@ -102,11 +105,6 @@ def generate_latest(registry: CollectorRegistry, emit_help: bool = False) -> byt
     by prometheus-client.
     """
 
-    # Trigger the cache metrics to be rescraped, which updates the common
-    # metrics but do not produce metrics themselves
-    for collector in caches.collectors_by_name.values():
-        collector.collect()
-
     output = []
 
     for metric in registry.collect():
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index a6c5cee45fd1..a9fa78da4976 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -179,7 +179,7 @@ async def _get_power_levels_and_sender_level(
         return pl_event.content if pl_event else {}, sender_level
 
     async def _get_mutual_relations(
-        self, event: EventBase, rules: Iterable[Tuple[PushRule, bool]]
+        self, parent_id: str, rules: Iterable[Tuple[PushRule, bool]]
     ) -> Dict[str, Set[Tuple[str, str]]]:
         """
         Fetch event metadata for events which related to the same event as the given event.
@@ -187,7 +187,7 @@ async def _get_mutual_relations(
         If the given event has no relation information, returns an empty dictionary.
 
         Args:
-            event_id: The event ID which is targeted by relations.
+            parent_id: The event ID which is targeted by relations.
             rules: The push rules which will be processed for this event.
 
         Returns:
@@ -201,12 +201,6 @@ async def _get_mutual_relations(
         if not self._relations_match_enabled:
             return {}
 
-        # If the event does not have a relation, then cannot have any mutual
-        # relations.
-        relation = relation_from_event(event)
-        if not relation:
-            return {}
-
         # Pre-filter to figure out which relation types are interesting.
         rel_types = set()
         for rule, enabled in rules:
@@ -227,9 +221,7 @@ async def _get_mutual_relations(
             return {}
 
         # If any valid rules were found, fetch the mutual relations.
-        return await self.store.get_mutual_event_relations(
-            relation.parent_id, rel_types
-        )
+        return await self.store.get_mutual_event_relations(parent_id, rel_types)
 
     @measure_func("action_for_event_by_user")
     async def action_for_event_by_user(
@@ -263,9 +255,17 @@ async def action_for_event_by_user(
             else None
         )
 
-        relations = await self._get_mutual_relations(
-            event, itertools.chain(*rules_by_user.values())
-        )
+        relation = relation_from_event(event)
+        # If the event does not have a relation, then cannot have any mutual
+        # relations or thread ID.
+        relations = {}
+        thread_id = "main"
+        if relation:
+            relations = await self._get_mutual_relations(
+                relation.parent_id, itertools.chain(*rules_by_user.values())
+            )
+            if relation.rel_type == RelationTypes.THREAD:
+                thread_id = relation.parent_id
 
         evaluator = PushRuleEvaluatorForEvent(
             event,
@@ -341,6 +341,7 @@ async def action_for_event_by_user(
             event.event_id,
             actions_by_user,
             count_as_unread_by_user,
+            thread_id,
         )
 
         logger.info(
diff --git a/synapse/rest/admin/__init__.py b/synapse/rest/admin/__init__.py
index fa3266720bcc..885669f9c779 100644
--- a/synapse/rest/admin/__init__.py
+++ b/synapse/rest/admin/__init__.py
@@ -61,9 +61,11 @@
     MakeRoomAdminRestServlet,
     RoomEventContextServlet,
     RoomMembersRestServlet,
+    RoomMessagesRestServlet,
     RoomRestServlet,
     RoomRestV2Servlet,
     RoomStateRestServlet,
+    RoomTimestampToEventRestServlet,
 )
 from synapse.rest.admin.server_notice_servlet import SendServerNoticeServlet
 from synapse.rest.admin.statistics import UserMediaStatisticsRestServlet
@@ -78,6 +80,7 @@
     SearchUsersRestServlet,
     ShadowBanRestServlet,
     UserAdminServlet,
+    UserByExternalId,
     UserMembershipRestServlet,
     UserRegisterServlet,
     UserRestServletV2,
@@ -271,6 +274,9 @@ def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     DestinationResetConnectionRestServlet(hs).register(http_server)
     DestinationRestServlet(hs).register(http_server)
     ListDestinationsRestServlet(hs).register(http_server)
+    RoomMessagesRestServlet(hs).register(http_server)
+    RoomTimestampToEventRestServlet(hs).register(http_server)
+    UserByExternalId(hs).register(http_server)
 
     # Some servlets only get registered for the main process.
     if hs.config.worker.worker_app is None:
diff --git a/synapse/rest/admin/rooms.py b/synapse/rest/admin/rooms.py
index 33d038dd8631..b1e79959cfad 100644
--- a/synapse/rest/admin/rooms.py
+++ b/synapse/rest/admin/rooms.py
@@ -38,6 +38,7 @@
 )
 from synapse.storage.databases.main.room import RoomSortOrder
 from synapse.storage.state import StateFilter
+from synapse.streams.config import PaginationConfig
 from synapse.types import JsonDict, RoomID, UserID, create_requester
 from synapse.util import json_decoder
 
@@ -872,3 +873,106 @@ async def on_PUT(
             await self._store.unblock_room(room_id)
 
         return HTTPStatus.OK, {"block": block}
+
+
+class RoomMessagesRestServlet(RestServlet):
+    """
+    Get messages list of a room.
+    """
+
+    PATTERNS = admin_patterns("/rooms/(?P<room_id>[^/]*)/messages$")
+
+    def __init__(self, hs: "HomeServer"):
+        self._hs = hs
+        self._clock = hs.get_clock()
+        self._pagination_handler = hs.get_pagination_handler()
+        self._auth = hs.get_auth()
+        self._store = hs.get_datastores().main
+
+    async def on_GET(
+        self, request: SynapseRequest, room_id: str
+    ) -> Tuple[int, JsonDict]:
+        requester = await self._auth.get_user_by_req(request)
+        await assert_user_is_admin(self._auth, requester)
+
+        pagination_config = await PaginationConfig.from_request(
+            self._store, request, default_limit=10
+        )
+        # Twisted will have processed the args by now.
+        assert request.args is not None
+        as_client_event = b"raw" not in request.args
+        filter_str = parse_string(request, "filter", encoding="utf-8")
+        if filter_str:
+            filter_json = urlparse.unquote(filter_str)
+            event_filter: Optional[Filter] = Filter(
+                self._hs, json_decoder.decode(filter_json)
+            )
+            if (
+                event_filter
+                and event_filter.filter_json.get("event_format", "client")
+                == "federation"
+            ):
+                as_client_event = False
+        else:
+            event_filter = None
+
+        msgs = await self._pagination_handler.get_messages(
+            room_id=room_id,
+            requester=requester,
+            pagin_config=pagination_config,
+            as_client_event=as_client_event,
+            event_filter=event_filter,
+            use_admin_priviledge=True,
+        )
+
+        return HTTPStatus.OK, msgs
+
+
+class RoomTimestampToEventRestServlet(RestServlet):
+    """
+    API endpoint to fetch the `event_id` of the closest event to the given
+    timestamp (`ts` query parameter) in the given direction (`dir` query
+    parameter).
+
+    Useful for cases like jump to date so you can start paginating messages from
+    a given date in the archive.
+
+    `ts` is a timestamp in milliseconds where we will find the closest event in
+    the given direction.
+
+    `dir` can be `f` or `b` to indicate forwards and backwards in time from the
+    given timestamp.
+
+    GET /_synapse/admin/v1/rooms/<roomID>/timestamp_to_event?ts=<timestamp>&dir=<direction>
+    {
+        "event_id": ...
+    }
+    """
+
+    PATTERNS = admin_patterns("/rooms/(?P<room_id>[^/]*)/timestamp_to_event$")
+
+    def __init__(self, hs: "HomeServer"):
+        self._auth = hs.get_auth()
+        self._store = hs.get_datastores().main
+        self._timestamp_lookup_handler = hs.get_timestamp_lookup_handler()
+
+    async def on_GET(
+        self, request: SynapseRequest, room_id: str
+    ) -> Tuple[int, JsonDict]:
+        requester = await self._auth.get_user_by_req(request)
+        await assert_user_is_admin(self._auth, requester)
+
+        timestamp = parse_integer(request, "ts", required=True)
+        direction = parse_string(request, "dir", default="f", allowed_values=["f", "b"])
+
+        (
+            event_id,
+            origin_server_ts,
+        ) = await self._timestamp_lookup_handler.get_event_for_timestamp(
+            requester, room_id, timestamp, direction
+        )
+
+        return HTTPStatus.OK, {
+            "event_id": event_id,
+            "origin_server_ts": origin_server_ts,
+        }
diff --git a/synapse/rest/admin/users.py b/synapse/rest/admin/users.py
index e42755e921ab..9d65b1c5e087 100644
--- a/synapse/rest/admin/users.py
+++ b/synapse/rest/admin/users.py
@@ -1165,3 +1165,30 @@ async def on_GET(
                 "rooms": by_room_data,
             },
         }
+
+
+class UserByExternalId(RestServlet):
+    """Find a user based on an external ID from an auth provider"""
+
+    PATTERNS = admin_patterns(
+        "/auth_providers/(?P<provider>[^/]*)/users/(?P<external_id>[^/]*)"
+    )
+
+    def __init__(self, hs: "HomeServer"):
+        self._auth = hs.get_auth()
+        self._store = hs.get_datastores().main
+
+    async def on_GET(
+        self,
+        request: SynapseRequest,
+        provider: str,
+        external_id: str,
+    ) -> Tuple[int, JsonDict]:
+        await assert_requester_is_admin(self._auth, request)
+
+        user_id = await self._store.get_user_by_external_id(provider, external_id)
+
+        if user_id is None:
+            raise NotFoundError("User not found")
+
+        return HTTPStatus.OK, {"user_id": user_id}
diff --git a/synapse/rest/client/account.py b/synapse/rest/client/account.py
index 1f9a8ccc2349..2db2a04f95df 100644
--- a/synapse/rest/client/account.py
+++ b/synapse/rest/client/account.py
@@ -15,10 +15,11 @@
 # limitations under the License.
 import logging
 import random
-from typing import TYPE_CHECKING, Optional, Tuple
+from typing import TYPE_CHECKING, List, Optional, Tuple
 from urllib.parse import urlparse
 
 from pydantic import StrictBool, StrictStr, constr
+from typing_extensions import Literal
 
 from twisted.web.server import Request
 
@@ -41,7 +42,12 @@
 from synapse.http.site import SynapseRequest
 from synapse.metrics import threepid_send_requests
 from synapse.push.mailer import Mailer
-from synapse.rest.client.models import AuthenticationData, EmailRequestTokenBody
+from synapse.rest.client.models import (
+    AuthenticationData,
+    ClientSecretStr,
+    EmailRequestTokenBody,
+    MsisdnRequestTokenBody,
+)
 from synapse.rest.models import RequestBodyModel
 from synapse.types import JsonDict
 from synapse.util.msisdn import phone_number_to_msisdn
@@ -400,23 +406,16 @@ def __init__(self, hs: "HomeServer"):
         self.identity_handler = hs.get_identity_handler()
 
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
-        body = parse_json_object_from_request(request)
-        assert_params_in_dict(
-            body, ["client_secret", "country", "phone_number", "send_attempt"]
+        body = parse_and_validate_json_object_from_request(
+            request, MsisdnRequestTokenBody
         )
-        client_secret = body["client_secret"]
-        assert_valid_client_secret(client_secret)
-
-        country = body["country"]
-        phone_number = body["phone_number"]
-        send_attempt = body["send_attempt"]
-        next_link = body.get("next_link")  # Optional param
-
-        msisdn = phone_number_to_msisdn(country, phone_number)
+        msisdn = phone_number_to_msisdn(body.country, body.phone_number)
 
         if not await check_3pid_allowed(self.hs, "msisdn", msisdn):
             raise SynapseError(
                 403,
+                # TODO: is this error message accurate? Looks like we've only rejected
+                #       this phone number, not necessarily all phone numbers
                 "Account phone numbers are not authorized on this server",
                 Codes.THREEPID_DENIED,
             )
@@ -425,9 +424,9 @@ async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
             request, "msisdn", msisdn
         )
 
-        if next_link:
+        if body.next_link:
             # Raise if the provided next_link value isn't valid
-            assert_valid_next_link(self.hs, next_link)
+            assert_valid_next_link(self.hs, body.next_link)
 
         existing_user_id = await self.store.get_user_id_by_threepid("msisdn", msisdn)
 
@@ -454,15 +453,15 @@ async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
 
         ret = await self.identity_handler.requestMsisdnToken(
             self.hs.config.registration.account_threepid_delegate_msisdn,
-            country,
-            phone_number,
-            client_secret,
-            send_attempt,
-            next_link,
+            body.country,
+            body.phone_number,
+            body.client_secret,
+            body.send_attempt,
+            body.next_link,
         )
 
         threepid_send_requests.labels(type="msisdn", reason="add_threepid").observe(
-            send_attempt
+            body.send_attempt
         )
 
         return 200, ret
@@ -630,6 +629,11 @@ def __init__(self, hs: "HomeServer"):
         self.auth = hs.get_auth()
         self.auth_handler = hs.get_auth_handler()
 
+    class PostBody(RequestBodyModel):
+        auth: Optional[AuthenticationData] = None
+        client_secret: ClientSecretStr
+        sid: StrictStr
+
     @interactive_auth_handler
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         if not self.hs.config.registration.enable_3pid_changes:
@@ -639,22 +643,17 @@ async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
 
         requester = await self.auth.get_user_by_req(request)
         user_id = requester.user.to_string()
-        body = parse_json_object_from_request(request)
-
-        assert_params_in_dict(body, ["client_secret", "sid"])
-        sid = body["sid"]
-        client_secret = body["client_secret"]
-        assert_valid_client_secret(client_secret)
+        body = parse_and_validate_json_object_from_request(request, self.PostBody)
 
         await self.auth_handler.validate_user_via_ui_auth(
             requester,
             request,
-            body,
+            body.dict(exclude_unset=True),
             "add a third-party identifier to your account",
         )
 
         validation_session = await self.identity_handler.validate_threepid_session(
-            client_secret, sid
+            body.client_secret, body.sid
         )
         if validation_session:
             await self.auth_handler.add_threepid(
@@ -679,23 +678,20 @@ def __init__(self, hs: "HomeServer"):
         self.identity_handler = hs.get_identity_handler()
         self.auth = hs.get_auth()
 
-    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
-        body = parse_json_object_from_request(request)
+    class PostBody(RequestBodyModel):
+        client_secret: ClientSecretStr
+        id_access_token: StrictStr
+        id_server: StrictStr
+        sid: StrictStr
 
-        assert_params_in_dict(
-            body, ["id_server", "sid", "id_access_token", "client_secret"]
-        )
-        id_server = body["id_server"]
-        sid = body["sid"]
-        id_access_token = body["id_access_token"]
-        client_secret = body["client_secret"]
-        assert_valid_client_secret(client_secret)
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
+        body = parse_and_validate_json_object_from_request(request, self.PostBody)
 
         requester = await self.auth.get_user_by_req(request)
         user_id = requester.user.to_string()
 
         await self.identity_handler.bind_threepid(
-            client_secret, sid, user_id, id_server, id_access_token
+            body.client_secret, body.sid, user_id, body.id_server, body.id_access_token
         )
 
         return 200, {}
@@ -711,23 +707,27 @@ def __init__(self, hs: "HomeServer"):
         self.auth = hs.get_auth()
         self.datastore = self.hs.get_datastores().main
 
+    class PostBody(RequestBodyModel):
+        address: StrictStr
+        id_server: Optional[StrictStr] = None
+        medium: Literal["email", "msisdn"]
+
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         """Unbind the given 3pid from a specific identity server, or identity servers that are
         known to have this 3pid bound
         """
         requester = await self.auth.get_user_by_req(request)
-        body = parse_json_object_from_request(request)
-        assert_params_in_dict(body, ["medium", "address"])
-
-        medium = body.get("medium")
-        address = body.get("address")
-        id_server = body.get("id_server")
+        body = parse_and_validate_json_object_from_request(request, self.PostBody)
 
         # Attempt to unbind the threepid from an identity server. If id_server is None, try to
         # unbind from all identity servers this threepid has been added to in the past
         result = await self.identity_handler.try_unbind_threepid(
             requester.user.to_string(),
-            {"address": address, "medium": medium, "id_server": id_server},
+            {
+                "address": body.address,
+                "medium": body.medium,
+                "id_server": body.id_server,
+            },
         )
         return 200, {"id_server_unbind_result": "success" if result else "no-support"}
 
@@ -741,21 +741,25 @@ def __init__(self, hs: "HomeServer"):
         self.auth = hs.get_auth()
         self.auth_handler = hs.get_auth_handler()
 
+    class PostBody(RequestBodyModel):
+        address: StrictStr
+        id_server: Optional[StrictStr] = None
+        medium: Literal["email", "msisdn"]
+
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         if not self.hs.config.registration.enable_3pid_changes:
             raise SynapseError(
                 400, "3PID changes are disabled on this server", Codes.FORBIDDEN
             )
 
-        body = parse_json_object_from_request(request)
-        assert_params_in_dict(body, ["medium", "address"])
+        body = parse_and_validate_json_object_from_request(request, self.PostBody)
 
         requester = await self.auth.get_user_by_req(request)
         user_id = requester.user.to_string()
 
         try:
             ret = await self.auth_handler.delete_threepid(
-                user_id, body["medium"], body["address"], body.get("id_server")
+                user_id, body.medium, body.address, body.id_server
             )
         except Exception:
             # NB. This endpoint should succeed if there is nothing to
@@ -845,17 +849,18 @@ def __init__(self, hs: "HomeServer"):
         self._auth = hs.get_auth()
         self._account_handler = hs.get_account_handler()
 
+    class PostBody(RequestBodyModel):
+        # TODO: we could validate that each user id is an mxid here, and/or parse it
+        #       as a UserID
+        user_ids: List[StrictStr]
+
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         await self._auth.get_user_by_req(request)
 
-        body = parse_json_object_from_request(request)
-        if "user_ids" not in body:
-            raise SynapseError(
-                400, "Required parameter 'user_ids' is missing", Codes.MISSING_PARAM
-            )
+        body = parse_and_validate_json_object_from_request(request, self.PostBody)
 
         statuses, failures = await self._account_handler.get_account_statuses(
-            body["user_ids"],
+            body.user_ids,
             allow_remote=True,
         )
 
diff --git a/synapse/rest/client/keys.py b/synapse/rest/client/keys.py
index a395694fa50f..f653d2a3e174 100644
--- a/synapse/rest/client/keys.py
+++ b/synapse/rest/client/keys.py
@@ -27,9 +27,9 @@
 )
 from synapse.http.site import SynapseRequest
 from synapse.logging.opentracing import log_kv, set_tag
+from synapse.rest.client._base import client_patterns, interactive_auth_handler
 from synapse.types import JsonDict, StreamToken
-
-from ._base import client_patterns, interactive_auth_handler
+from synapse.util.cancellation import cancellable
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -156,6 +156,7 @@ def __init__(self, hs: "HomeServer"):
         self.auth = hs.get_auth()
         self.e2e_keys_handler = hs.get_e2e_keys_handler()
 
+    @cancellable
     async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         user_id = requester.user.to_string()
@@ -199,6 +200,7 @@ def __init__(self, hs: "HomeServer"):
         self.device_handler = hs.get_device_handler()
         self.store = hs.get_datastores().main
 
+    @cancellable
     async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
 
diff --git a/synapse/rest/client/models.py b/synapse/rest/client/models.py
index 31506029973a..3d7940b0fc50 100644
--- a/synapse/rest/client/models.py
+++ b/synapse/rest/client/models.py
@@ -25,8 +25,8 @@ class AuthenticationData(RequestBodyModel):
 
     (The name "Authentication Data" is taken directly from the spec.)
 
-    Additional keys will be present, depending on the `type` field. Use `.dict()` to
-    access them.
+    Additional keys will be present, depending on the `type` field. Use
+    `.dict(exclude_unset=True)` to access them.
     """
 
     class Config:
@@ -36,18 +36,20 @@ class Config:
     type: Optional[StrictStr] = None
 
 
-class EmailRequestTokenBody(RequestBodyModel):
-    if TYPE_CHECKING:
-        client_secret: StrictStr
-    else:
-        # See also assert_valid_client_secret()
-        client_secret: constr(
-            regex="[0-9a-zA-Z.=_-]",  # noqa: F722
-            min_length=0,
-            max_length=255,
-            strict=True,
-        )
-    email: StrictStr
+if TYPE_CHECKING:
+    ClientSecretStr = StrictStr
+else:
+    # See also assert_valid_client_secret()
+    ClientSecretStr = constr(
+        regex="[0-9a-zA-Z.=_-]",  # noqa: F722
+        min_length=1,
+        max_length=255,
+        strict=True,
+    )
+
+
+class ThreepidRequestTokenBody(RequestBodyModel):
+    client_secret: ClientSecretStr
     id_server: Optional[StrictStr]
     id_access_token: Optional[StrictStr]
     next_link: Optional[StrictStr]
@@ -61,9 +63,25 @@ def token_required_for_identity_server(
             raise ValueError("id_access_token is required if an id_server is supplied.")
         return token
 
+
+class EmailRequestTokenBody(ThreepidRequestTokenBody):
+    email: StrictStr
+
     # Canonicalise the email address. The addresses are all stored canonicalised
     # in the database. This allows the user to reset his password without having to
     # know the exact spelling (eg. upper and lower case) of address in the database.
     # Without this, an email stored in the database as "foo@bar.com" would cause
     # user requests for "FOO@bar.com" to raise a Not Found error.
     _email_validator = validator("email", allow_reuse=True)(validate_email)
+
+
+if TYPE_CHECKING:
+    ISO3116_1_Alpha_2 = StrictStr
+else:
+    # Per spec: two-letter uppercase ISO-3166-1-alpha-2
+    ISO3116_1_Alpha_2 = constr(regex="[A-Z]{2}", strict=True)
+
+
+class MsisdnRequestTokenBody(ThreepidRequestTokenBody):
+    country: ISO3116_1_Alpha_2
+    phone_number: StrictStr
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 9dd3c8d4bbd4..328c0c547794 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -19,6 +19,8 @@
 from io import BytesIO
 from typing import IO, TYPE_CHECKING, Dict, List, Optional, Set, Tuple
 
+from matrix_common.types.mxc_uri import MXCUri
+
 import twisted.internet.error
 import twisted.web.http
 from twisted.internet.defer import Deferred
@@ -186,7 +188,7 @@ async def create_content(
         content: IO,
         content_length: int,
         auth_user: UserID,
-    ) -> str:
+    ) -> MXCUri:
         """Store uploaded content for a local user and return the mxc URL
 
         Args:
@@ -219,7 +221,7 @@ async def create_content(
 
         await self._generate_thumbnails(None, media_id, media_id, media_type)
 
-        return "mxc://%s/%s" % (self.server_name, media_id)
+        return MXCUri(self.server_name, media_id)
 
     async def get_local_media(
         self, request: SynapseRequest, media_id: str, name: Optional[str]
diff --git a/synapse/rest/media/v1/upload_resource.py b/synapse/rest/media/v1/upload_resource.py
index e73e431dc9f1..97548b54e504 100644
--- a/synapse/rest/media/v1/upload_resource.py
+++ b/synapse/rest/media/v1/upload_resource.py
@@ -101,6 +101,8 @@ async def _async_render_POST(self, request: SynapseRequest) -> None:
             # the default 404, as that would just be confusing.
             raise SynapseError(400, "Bad content")
 
-        logger.info("Uploaded content with URI %r", content_uri)
+        logger.info("Uploaded content with URI '%s'", content_uri)
 
-        respond_with_json(request, 200, {"content_uri": content_uri}, send_cors=True)
+        respond_with_json(
+            request, 200, {"content_uri": str(content_uri)}, send_cors=True
+        )
diff --git a/synapse/server.py b/synapse/server.py
index dc5e5379b8c7..46d448240901 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -342,7 +342,17 @@ def is_mine(self, domain_specific_string: DomainSpecificString) -> bool:
         return domain_specific_string.domain == self.hostname
 
     def is_mine_id(self, string: str) -> bool:
-        return string.split(":", 1)[1] == self.hostname
+        """Determines whether a user ID or room alias originates from this homeserver.
+
+        Returns:
+            `True` if the hostname part of the user ID or room alias matches this
+            homeserver.
+            `False` otherwise, or if the user ID or room alias is malformed.
+        """
+        localpart_hostname = string.split(":", 1)
+        if len(localpart_hostname) < 2:
+            return False
+        return localpart_hostname[1] == self.hostname
 
     @cache_in_self
     def get_clock(self) -> Clock:
diff --git a/synapse/state/v2.py b/synapse/state/v2.py
index af03851c7142..1b9d7d84576e 100644
--- a/synapse/state/v2.py
+++ b/synapse/state/v2.py
@@ -577,6 +577,21 @@ async def _iterative_auth_checks(
                 if ev.rejected_reason is None:
                     auth_events[key] = event_map[ev_id]
 
+        if event.rejected_reason is not None:
+            # Do not admit previously rejected events into state.
+            # TODO: This isn't spec compliant. Events that were previously rejected due
+            #       to failing auth checks at their state, but pass auth checks during
+            #       state resolution should be accepted. Synapse does not handle the
+            #       change of rejection status well, so we preserve the previous
+            #       rejection status for now.
+            #
+            #       Note that events rejected for non-state reasons, such as having the
+            #       wrong auth events, should remain rejected.
+            #
+            #       https://spec.matrix.org/v1.2/rooms/v9/#rejected-events
+            #       https://github.com/matrix-org/synapse/issues/13797
+            continue
+
         try:
             event_auth.check_state_dependent_auth_rules(
                 event,
diff --git a/synapse/storage/background_updates.py b/synapse/storage/background_updates.py
index 555b4e77d2d8..bf5e7ee7be7e 100644
--- a/synapse/storage/background_updates.py
+++ b/synapse/storage/background_updates.py
@@ -533,6 +533,7 @@ def register_background_index_update(
             index_name: name of index to add
             table: table to add index to
             columns: columns/expressions to include in index
+            where_clause: A WHERE clause to specify a partial unique index.
             unique: true to make a UNIQUE index
             psql_only: true to only create this index on psql databases (useful
                 for virtual sqlite tables)
@@ -581,9 +582,6 @@ def create_index_psql(conn: Connection) -> None:
         def create_index_sqlite(conn: Connection) -> None:
             # Sqlite doesn't support concurrent creation of indexes.
             #
-            # We don't use partial indices on SQLite as it wasn't introduced
-            # until 3.8, and wheezy and CentOS 7 have 3.7
-            #
             # We assume that sqlite doesn't give us invalid indices; however
             # we may still end up with the index existing but the
             # background_updates not having been recorded if synapse got shut
@@ -591,12 +589,13 @@ def create_index_sqlite(conn: Connection) -> None:
             # has supported CREATE TABLE|INDEX IF NOT EXISTS since 3.3.0.)
             sql = (
                 "CREATE %(unique)s INDEX IF NOT EXISTS %(name)s ON %(table)s"
-                " (%(columns)s)"
+                " (%(columns)s) %(where_clause)s"
             ) % {
                 "unique": "UNIQUE" if unique else "",
                 "name": index_name,
                 "table": table,
                 "columns": ", ".join(columns),
+                "where_clause": "WHERE " + where_clause if where_clause else "",
             }
 
             c = conn.cursor()
diff --git a/synapse/storage/controllers/persist_events.py b/synapse/storage/controllers/persist_events.py
index dad3731b9b50..501dbbc99011 100644
--- a/synapse/storage/controllers/persist_events.py
+++ b/synapse/storage/controllers/persist_events.py
@@ -598,9 +598,9 @@ async def _persist_event_batch(
             # room
             state_delta_for_room: Dict[str, DeltaState] = {}
 
-            # Set of remote users which were in rooms the server has left. We
-            # should check if we still share any rooms and if not we mark their
-            # device lists as stale.
+            # Set of remote users which were in rooms the server has left or who may
+            # have left rooms the server is in. We should check if we still share any
+            # rooms and if not we mark their device lists as stale.
             potentially_left_users: Set[str] = set()
 
             if not backfilled:
@@ -725,6 +725,20 @@ async def _persist_event_batch(
                                 current_state = {}
                                 delta.no_longer_in_room = True
 
+                            # Add all remote users that might have left rooms.
+                            potentially_left_users.update(
+                                user_id
+                                for event_type, user_id in delta.to_delete
+                                if event_type == EventTypes.Member
+                                and not self.is_mine_id(user_id)
+                            )
+                            potentially_left_users.update(
+                                user_id
+                                for event_type, user_id in delta.to_insert.keys()
+                                if event_type == EventTypes.Member
+                                and not self.is_mine_id(user_id)
+                            )
+
                             state_delta_for_room[room_id] = delta
 
             await self.persist_events_store._persist_events_and_state_updates(
diff --git a/synapse/storage/controllers/state.py b/synapse/storage/controllers/state.py
index ba5380ce3e91..bbe568bf053e 100644
--- a/synapse/storage/controllers/state.py
+++ b/synapse/storage/controllers/state.py
@@ -36,6 +36,7 @@
     PartialStateEventsTracker,
 )
 from synapse.types import MutableStateMap, StateMap
+from synapse.util.cancellation import cancellable
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -229,6 +230,7 @@ async def get_state_for_events(
 
     @trace
     @tag_args
+    @cancellable
     async def get_state_ids_for_events(
         self,
         event_ids: Collection[str],
@@ -350,6 +352,7 @@ def get_state_for_groups(
 
     @trace
     @tag_args
+    @cancellable
     async def get_state_group_for_events(
         self,
         event_ids: Collection[str],
@@ -398,6 +401,7 @@ async def store_state_group(
             event_id, room_id, prev_group, delta_ids, current_state_ids
         )
 
+    @cancellable
     async def get_current_state_ids(
         self,
         room_id: str,
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index b394a6658b09..921cd4dc5ee0 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -533,15 +533,14 @@ def __init__(
         if isinstance(self.engine, Sqlite3Engine):
             self._unsafe_to_upsert_tables.add("user_directory_search")
 
-        if self.engine.can_native_upsert:
-            # Check ASAP (and then later, every 1s) to see if we have finished
-            # background updates of tables that aren't safe to update.
-            self._clock.call_later(
-                0.0,
-                run_as_background_process,
-                "upsert_safety_check",
-                self._check_safe_to_upsert,
-            )
+        # Check ASAP (and then later, every 1s) to see if we have finished
+        # background updates of tables that aren't safe to update.
+        self._clock.call_later(
+            0.0,
+            run_as_background_process,
+            "upsert_safety_check",
+            self._check_safe_to_upsert,
+        )
 
     def name(self) -> str:
         "Return the name of this database"
@@ -1160,11 +1159,8 @@ async def simple_upsert(
         attempts = 0
         while True:
             try:
-                # We can autocommit if we are going to use native upserts
-                autocommit = (
-                    self.engine.can_native_upsert
-                    and table not in self._unsafe_to_upsert_tables
-                )
+                # We can autocommit if it is safe to upsert
+                autocommit = table not in self._unsafe_to_upsert_tables
 
                 return await self.runInteraction(
                     desc,
@@ -1195,11 +1191,12 @@ def simple_upsert_txn(
         keyvalues: Dict[str, Any],
         values: Dict[str, Any],
         insertion_values: Optional[Dict[str, Any]] = None,
+        where_clause: Optional[str] = None,
         lock: bool = True,
     ) -> bool:
         """
         Pick the UPSERT method which works best on the platform. Either the
-        native one (Pg9.5+, recent SQLites), or fall back to an emulated method.
+        native one (Pg9.5+, SQLite >= 3.24), or fall back to an emulated method.
 
         Args:
             txn: The transaction to use.
@@ -1207,16 +1204,23 @@ def simple_upsert_txn(
             keyvalues: The unique key tables and their new values
             values: The nonunique columns and their new values
             insertion_values: additional key/values to use only when inserting
-            lock: True to lock the table when doing the upsert.
+            where_clause: An index predicate to apply to the upsert.
+            lock: True to lock the table when doing the upsert. Unused when performing
+                a native upsert.
         Returns:
             Returns True if a row was inserted or updated (i.e. if `values` is
             not empty then this always returns True)
         """
         insertion_values = insertion_values or {}
 
-        if self.engine.can_native_upsert and table not in self._unsafe_to_upsert_tables:
+        if table not in self._unsafe_to_upsert_tables:
             return self.simple_upsert_txn_native_upsert(
-                txn, table, keyvalues, values, insertion_values=insertion_values
+                txn,
+                table,
+                keyvalues,
+                values,
+                insertion_values=insertion_values,
+                where_clause=where_clause,
             )
         else:
             return self.simple_upsert_txn_emulated(
@@ -1225,6 +1229,7 @@ def simple_upsert_txn(
                 keyvalues,
                 values,
                 insertion_values=insertion_values,
+                where_clause=where_clause,
                 lock=lock,
             )
 
@@ -1235,6 +1240,7 @@ def simple_upsert_txn_emulated(
         keyvalues: Dict[str, Any],
         values: Dict[str, Any],
         insertion_values: Optional[Dict[str, Any]] = None,
+        where_clause: Optional[str] = None,
         lock: bool = True,
     ) -> bool:
         """
@@ -1243,6 +1249,7 @@ def simple_upsert_txn_emulated(
             keyvalues: The unique key tables and their new values
             values: The nonunique columns and their new values
             insertion_values: additional key/values to use only when inserting
+            where_clause: An index predicate to apply to the upsert.
             lock: True to lock the table when doing the upsert.
         Returns:
             Returns True if a row was inserted or updated (i.e. if `values` is
@@ -1262,14 +1269,17 @@ def _getwhere(key: str) -> str:
             else:
                 return "%s = ?" % (key,)
 
+        # Generate a where clause of each keyvalue and optionally the provided
+        # index predicate.
+        where = [_getwhere(k) for k in keyvalues]
+        if where_clause:
+            where.append(where_clause)
+
         if not values:
             # If `values` is empty, then all of the values we care about are in
             # the unique key, so there is nothing to UPDATE. We can just do a
             # SELECT instead to see if it exists.
-            sql = "SELECT 1 FROM %s WHERE %s" % (
-                table,
-                " AND ".join(_getwhere(k) for k in keyvalues),
-            )
+            sql = "SELECT 1 FROM %s WHERE %s" % (table, " AND ".join(where))
             sqlargs = list(keyvalues.values())
             txn.execute(sql, sqlargs)
             if txn.fetchall():
@@ -1280,7 +1290,7 @@ def _getwhere(key: str) -> str:
             sql = "UPDATE %s SET %s WHERE %s" % (
                 table,
                 ", ".join("%s = ?" % (k,) for k in values),
-                " AND ".join(_getwhere(k) for k in keyvalues),
+                " AND ".join(where),
             )
             sqlargs = list(values.values()) + list(keyvalues.values())
 
@@ -1310,6 +1320,7 @@ def simple_upsert_txn_native_upsert(
         keyvalues: Dict[str, Any],
         values: Dict[str, Any],
         insertion_values: Optional[Dict[str, Any]] = None,
+        where_clause: Optional[str] = None,
     ) -> bool:
         """
         Use the native UPSERT functionality in PostgreSQL.
@@ -1319,6 +1330,7 @@ def simple_upsert_txn_native_upsert(
             keyvalues: The unique key tables and their new values
             values: The nonunique columns and their new values
             insertion_values: additional key/values to use only when inserting
+            where_clause: An index predicate to apply to the upsert.
 
         Returns:
             Returns True if a row was inserted or updated (i.e. if `values` is
@@ -1334,11 +1346,12 @@ def simple_upsert_txn_native_upsert(
             allvalues.update(values)
             latter = "UPDATE SET " + ", ".join(k + "=EXCLUDED." + k for k in values)
 
-        sql = ("INSERT INTO %s (%s) VALUES (%s) ON CONFLICT (%s) DO %s") % (
+        sql = "INSERT INTO %s (%s) VALUES (%s) ON CONFLICT (%s) %s DO %s" % (
             table,
             ", ".join(k for k in allvalues),
             ", ".join("?" for _ in allvalues),
             ", ".join(k for k in keyvalues),
+            f"WHERE {where_clause}" if where_clause else "",
             latter,
         )
         txn.execute(sql, list(allvalues.values()))
@@ -1365,14 +1378,12 @@ async def simple_upsert_many(
             value_names: The value column names
             value_values: A list of each row's value column values.
                 Ignored if value_names is empty.
-            lock: True to lock the table when doing the upsert. Unused if the database engine
-                supports native upserts.
+            lock: True to lock the table when doing the upsert. Unused when performing
+                a native upsert.
         """
 
-        # We can autocommit if we are going to use native upserts
-        autocommit = (
-            self.engine.can_native_upsert and table not in self._unsafe_to_upsert_tables
-        )
+        # We can autocommit if it safe to upsert
+        autocommit = table not in self._unsafe_to_upsert_tables
 
         await self.runInteraction(
             desc,
@@ -1406,10 +1417,10 @@ def simple_upsert_many_txn(
             value_names: The value column names
             value_values: A list of each row's value column values.
                 Ignored if value_names is empty.
-            lock: True to lock the table when doing the upsert. Unused if the database engine
-                supports native upserts.
+            lock: True to lock the table when doing the upsert. Unused when performing
+                a native upsert.
         """
-        if self.engine.can_native_upsert and table not in self._unsafe_to_upsert_tables:
+        if table not in self._unsafe_to_upsert_tables:
             return self.simple_upsert_many_txn_native_upsert(
                 txn, table, key_names, key_values, value_names, value_values
             )
diff --git a/synapse/storage/databases/main/devices.py b/synapse/storage/databases/main/devices.py
index ca0fe8c4bea3..5d700ca6c307 100644
--- a/synapse/storage/databases/main/devices.py
+++ b/synapse/storage/databases/main/devices.py
@@ -53,6 +53,7 @@
 from synapse.util.caches.descriptors import cached, cachedList
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.stream_change_cache import StreamChangeCache
+from synapse.util.cancellation import cancellable
 from synapse.util.iterutils import batch_iter
 from synapse.util.stringutils import shortstr
 
@@ -668,6 +669,7 @@ def get_device_stream_token(self) -> int:
         ...
 
     @trace
+    @cancellable
     async def get_user_devices_from_cache(
         self, query_list: List[Tuple[str, Optional[str]]]
     ) -> Tuple[Set[str], Dict[str, Dict[str, JsonDict]]]:
@@ -743,6 +745,7 @@ def get_cached_device_list_changes(
 
         return self._device_list_stream_cache.get_all_entities_changed(from_key)
 
+    @cancellable
     async def get_users_whose_devices_changed(
         self,
         from_key: int,
@@ -1221,6 +1224,7 @@ async def _get_min_device_lists_changes_in_room(self) -> int:
             desc="get_min_device_lists_changes_in_room",
         )
 
+    @cancellable
     async def get_device_list_changes_in_rooms(
         self, room_ids: Collection[str], from_id: int
     ) -> Optional[Set[str]]:
diff --git a/synapse/storage/databases/main/end_to_end_keys.py b/synapse/storage/databases/main/end_to_end_keys.py
index 46c0d061579e..8e9e1b0b4b41 100644
--- a/synapse/storage/databases/main/end_to_end_keys.py
+++ b/synapse/storage/databases/main/end_to_end_keys.py
@@ -50,6 +50,7 @@
 from synapse.types import JsonDict
 from synapse.util import json_encoder
 from synapse.util.caches.descriptors import cached, cachedList
+from synapse.util.cancellation import cancellable
 from synapse.util.iterutils import batch_iter
 
 if TYPE_CHECKING:
@@ -135,6 +136,7 @@ async def get_e2e_device_keys_for_federation_query(
         return now_stream_id, []
 
     @trace
+    @cancellable
     async def get_e2e_device_keys_for_cs_api(
         self, query_list: List[Tuple[str, Optional[str]]]
     ) -> Dict[str, Dict[str, JsonDict]]:
@@ -197,6 +199,7 @@ async def get_e2e_device_keys_and_signatures(
         ...
 
     @trace
+    @cancellable
     async def get_e2e_device_keys_and_signatures(
         self,
         query_list: Collection[Tuple[str, Optional[str]]],
@@ -887,6 +890,7 @@ def _get_e2e_cross_signing_signatures_txn(
 
         return keys
 
+    @cancellable
     async def get_e2e_cross_signing_keys_bulk(
         self, user_ids: List[str], from_user_id: Optional[str] = None
     ) -> Dict[str, Optional[Dict[str, JsonDict]]]:
@@ -902,7 +906,6 @@ async def get_e2e_cross_signing_keys_bulk(
             keys were not found, either their user ID will not be in the dict,
             or their user ID will map to None.
         """
-
         result = await self._get_bare_e2e_cross_signing_keys_bulk(user_ids)
 
         if from_user_id:
diff --git a/synapse/storage/databases/main/event_federation.py b/synapse/storage/databases/main/event_federation.py
index c836078da683..ef477978ed63 100644
--- a/synapse/storage/databases/main/event_federation.py
+++ b/synapse/storage/databases/main/event_federation.py
@@ -48,6 +48,7 @@
 from synapse.util import json_encoder
 from synapse.util.caches.descriptors import cached
 from synapse.util.caches.lrucache import LruCache
+from synapse.util.cancellation import cancellable
 from synapse.util.iterutils import batch_iter
 
 if TYPE_CHECKING:
@@ -976,6 +977,7 @@ def _get_min_depth_interaction(
 
         return int(min_depth) if min_depth is not None else None
 
+    @cancellable
     async def get_forward_extremities_for_room_at_stream_ordering(
         self, room_id: str, stream_ordering: int
     ) -> List[str]:
@@ -1292,6 +1294,51 @@ def _get_backfill_events(
 
         return event_id_results
 
+    @trace
+    async def record_event_failed_pull_attempt(
+        self, room_id: str, event_id: str, cause: str
+    ) -> None:
+        """
+        Record when we fail to pull an event over federation.
+
+        This information allows us to be more intelligent when we decide to
+        retry (we don't need to fail over and over) and we can process that
+        event in the background so we don't block on it each time.
+
+        Args:
+            room_id: The room where the event failed to pull from
+            event_id: The event that failed to be fetched or processed
+            cause: The error message or reason that we failed to pull the event
+        """
+        await self.db_pool.runInteraction(
+            "record_event_failed_pull_attempt",
+            self._record_event_failed_pull_attempt_upsert_txn,
+            room_id,
+            event_id,
+            cause,
+            db_autocommit=True,  # Safe as it's a single upsert
+        )
+
+    def _record_event_failed_pull_attempt_upsert_txn(
+        self,
+        txn: LoggingTransaction,
+        room_id: str,
+        event_id: str,
+        cause: str,
+    ) -> None:
+        sql = """
+            INSERT INTO event_failed_pull_attempts (
+                room_id, event_id, num_attempts, last_attempt_ts, last_cause
+            )
+                VALUES (?, ?, ?, ?, ?)
+            ON CONFLICT (room_id, event_id) DO UPDATE SET
+                num_attempts=event_failed_pull_attempts.num_attempts + 1,
+                last_attempt_ts=EXCLUDED.last_attempt_ts,
+                last_cause=EXCLUDED.last_cause;
+        """
+
+        txn.execute(sql, (room_id, event_id, 1, self._clock.time_msec(), cause))
+
     async def get_missing_events(
         self,
         room_id: str,
@@ -1606,7 +1653,7 @@ async def prune_staged_events_in_room(
                 logger.info("Invalid prev_events for %s", event_id)
                 continue
 
-            if room_version.event_format == EventFormatVersions.V1:
+            if room_version.event_format == EventFormatVersions.ROOM_V1_V2:
                 for prev_event_tuple in prev_events:
                     if (
                         not isinstance(prev_event_tuple, list)
diff --git a/synapse/storage/databases/main/event_push_actions.py b/synapse/storage/databases/main/event_push_actions.py
index b13db9d0c14c..fb49e405efdc 100644
--- a/synapse/storage/databases/main/event_push_actions.py
+++ b/synapse/storage/databases/main/event_push_actions.py
@@ -98,6 +98,7 @@
 )
 from synapse.storage.databases.main.receipts import ReceiptsWorkerStore
 from synapse.storage.databases.main.stream import StreamWorkerStore
+from synapse.types import JsonDict
 from synapse.util import json_encoder
 from synapse.util.caches.descriptors import cached
 
@@ -231,6 +232,104 @@ def __init__(
             replaces_index="event_push_summary_user_rm",
         )
 
+        self.db_pool.updates.register_background_index_update(
+            "event_push_summary_unique_index2",
+            index_name="event_push_summary_unique_index2",
+            table="event_push_summary",
+            columns=["user_id", "room_id", "thread_id"],
+            unique=True,
+        )
+
+        self.db_pool.updates.register_background_update_handler(
+            "event_push_backfill_thread_id",
+            self._background_backfill_thread_id,
+        )
+
+    async def _background_backfill_thread_id(
+        self, progress: JsonDict, batch_size: int
+    ) -> int:
+        """
+        Fill in the thread_id field for event_push_actions and event_push_summary.
+
+        This is preparatory so that it can be made non-nullable in the future.
+
+        Because all current (null) data is done in an unthreaded manner this
+        simply assumes it is on the "main" timeline. Since event_push_actions
+        are periodically cleared it is not possible to correctly re-calculate
+        the thread_id.
+        """
+        event_push_actions_done = progress.get("event_push_actions_done", False)
+
+        def add_thread_id_txn(
+            txn: LoggingTransaction, table_name: str, start_stream_ordering: int
+        ) -> int:
+            sql = f"""
+            SELECT stream_ordering
+            FROM {table_name}
+            WHERE
+                thread_id IS NULL
+                AND stream_ordering > ?
+            ORDER BY stream_ordering
+            LIMIT ?
+            """
+            txn.execute(sql, (start_stream_ordering, batch_size))
+
+            # No more rows to process.
+            rows = txn.fetchall()
+            if not rows:
+                progress[f"{table_name}_done"] = True
+                self.db_pool.updates._background_update_progress_txn(
+                    txn, "event_push_backfill_thread_id", progress
+                )
+                return 0
+
+            # Update the thread ID for any of those rows.
+            max_stream_ordering = rows[-1][0]
+
+            sql = f"""
+            UPDATE {table_name}
+            SET thread_id = 'main'
+            WHERE stream_ordering <= ? AND thread_id IS NULL
+            """
+            txn.execute(sql, (max_stream_ordering,))
+
+            # Update progress.
+            processed_rows = txn.rowcount
+            progress[f"max_{table_name}_stream_ordering"] = max_stream_ordering
+            self.db_pool.updates._background_update_progress_txn(
+                txn, "event_push_backfill_thread_id", progress
+            )
+
+            return processed_rows
+
+        # First update the event_push_actions table, then the event_push_summary table.
+        #
+        # Note that the event_push_actions_staging table is ignored since it is
+        # assumed that items in that table will only exist for a short period of
+        # time.
+        if not event_push_actions_done:
+            result = await self.db_pool.runInteraction(
+                "event_push_backfill_thread_id",
+                add_thread_id_txn,
+                "event_push_actions",
+                progress.get("max_event_push_actions_stream_ordering", 0),
+            )
+        else:
+            result = await self.db_pool.runInteraction(
+                "event_push_backfill_thread_id",
+                add_thread_id_txn,
+                "event_push_summary",
+                progress.get("max_event_push_summary_stream_ordering", 0),
+            )
+
+            # Only done after the event_push_summary table is done.
+            if not result:
+                await self.db_pool.updates._end_background_update(
+                    "event_push_backfill_thread_id"
+                )
+
+        return result
+
     @cached(tree=True, max_entries=5000)
     async def get_unread_event_push_actions_by_room_for_user(
         self,
@@ -668,6 +767,7 @@ async def add_push_actions_to_staging(
         event_id: str,
         user_id_actions: Dict[str, Collection[Union[Mapping, str]]],
         count_as_unread_by_user: Dict[str, bool],
+        thread_id: str,
     ) -> None:
         """Add the push actions for the event to the push action staging area.
 
@@ -676,6 +776,7 @@ async def add_push_actions_to_staging(
             user_id_actions: A mapping of user_id to list of push actions, where
                 an action can either be a string or dict.
             count_as_unread: Whether this event should increment unread counts.
+            thread_id: The thread this event is parent of, if applicable.
         """
         if not user_id_actions:
             return
@@ -684,7 +785,7 @@ async def add_push_actions_to_staging(
         # can be used to insert into the `event_push_actions_staging` table.
         def _gen_entry(
             user_id: str, actions: Collection[Union[Mapping, str]]
-        ) -> Tuple[str, str, str, int, int, int]:
+        ) -> Tuple[str, str, str, int, int, int, str]:
             is_highlight = 1 if _action_has_highlight(actions) else 0
             notif = 1 if "notify" in actions else 0
             return (
@@ -694,11 +795,20 @@ def _gen_entry(
                 notif,  # notif column
                 is_highlight,  # highlight column
                 int(count_as_unread_by_user[user_id]),  # unread column
+                thread_id,  # thread_id column
             )
 
         await self.db_pool.simple_insert_many(
             "event_push_actions_staging",
-            keys=("event_id", "user_id", "actions", "notif", "highlight", "unread"),
+            keys=(
+                "event_id",
+                "user_id",
+                "actions",
+                "notif",
+                "highlight",
+                "unread",
+                "thread_id",
+            ),
             values=[
                 _gen_entry(user_id, actions)
                 for user_id, actions in user_id_actions.items()
@@ -982,6 +1092,8 @@ def _handle_new_receipts_for_notifs_txn(self, txn: LoggingTransaction) -> bool:
             )
 
             # Replace the previous summary with the new counts.
+            #
+            # TODO(threads): Upsert per-thread instead of setting them all to main.
             self.db_pool.simple_upsert_txn(
                 txn,
                 table="event_push_summary",
@@ -991,6 +1103,7 @@ def _handle_new_receipts_for_notifs_txn(self, txn: LoggingTransaction) -> bool:
                     "unread_count": unread_count,
                     "stream_ordering": old_rotate_stream_ordering,
                     "last_receipt_stream_ordering": stream_ordering,
+                    "thread_id": "main",
                 },
             )
 
@@ -1139,17 +1252,19 @@ def _rotate_notifs_before_txn(
 
         logger.info("Rotating notifications, handling %d rows", len(summaries))
 
+        # TODO(threads): Update on a per-thread basis.
         self.db_pool.simple_upsert_many_txn(
             txn,
             table="event_push_summary",
             key_names=("user_id", "room_id"),
             key_values=[(user_id, room_id) for user_id, room_id in summaries],
-            value_names=("notif_count", "unread_count", "stream_ordering"),
+            value_names=("notif_count", "unread_count", "stream_ordering", "thread_id"),
             value_values=[
                 (
                     summary.notif_count,
                     summary.unread_count,
                     summary.stream_ordering,
+                    "main",
                 )
                 for summary in summaries.values()
             ],
@@ -1256,7 +1371,6 @@ def __init__(
             table="event_push_actions",
             columns=["highlight", "stream_ordering"],
             where_clause="highlight=0",
-            psql_only=True,
         )
 
     async def get_push_actions_for_user(
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index 874b0e122401..cf60a9293c26 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -2196,9 +2196,9 @@ def _set_push_actions_for_event_and_users_txn(
         sql = """
             INSERT INTO event_push_actions (
                 room_id, event_id, user_id, actions, stream_ordering,
-                topological_ordering, notif, highlight, unread
+                topological_ordering, notif, highlight, unread, thread_id
             )
-            SELECT ?, event_id, user_id, actions, ?, ?, notif, highlight, unread
+            SELECT ?, event_id, user_id, actions, ?, ?, notif, highlight, unread, thread_id
             FROM event_push_actions_staging
             WHERE event_id = ?
         """
@@ -2439,17 +2439,31 @@ def _update_backward_extremeties(
             "DELETE FROM event_backward_extremities"
             " WHERE event_id = ? AND room_id = ?"
         )
+        backward_extremity_tuples_to_remove = [
+            (ev.event_id, ev.room_id)
+            for ev in events
+            if not ev.internal_metadata.is_outlier()
+            # If we encountered an event with no prev_events, then we might
+            # as well remove it now because it won't ever have anything else
+            # to backfill from.
+            or len(ev.prev_event_ids()) == 0
+        ]
         txn.execute_batch(
             query,
-            [
-                (ev.event_id, ev.room_id)
-                for ev in events
-                if not ev.internal_metadata.is_outlier()
-                # If we encountered an event with no prev_events, then we might
-                # as well remove it now because it won't ever have anything else
-                # to backfill from.
-                or len(ev.prev_event_ids()) == 0
-            ],
+            backward_extremity_tuples_to_remove,
+        )
+
+        # Clear out the failed backfill attempts after we successfully pulled
+        # the event. Since we no longer need these events as backward
+        # extremities, it also means that they won't be backfilled from again so
+        # we no longer need to store the backfill attempts around it.
+        query = """
+            DELETE FROM event_failed_pull_attempts
+            WHERE event_id = ? and room_id = ?
+        """
+        txn.execute_batch(
+            query,
+            backward_extremity_tuples_to_remove,
         )
 
 
diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py
index 901857a88c27..aeed89b13080 100644
--- a/synapse/storage/databases/main/events_worker.py
+++ b/synapse/storage/databases/main/events_worker.py
@@ -83,6 +83,7 @@
 from synapse.util.caches.descriptors import cached, cachedList
 from synapse.util.caches.lrucache import AsyncLruCache
 from synapse.util.caches.redis_caches import RedisLruCache
+from synapse.util.cancellation import cancellable
 from synapse.util.iterutils import batch_iter
 from synapse.util.metrics import Measure
 
@@ -352,6 +353,7 @@ async def get_event(
     ) -> Optional[EventBase]:
         ...
 
+    @cancellable
     async def get_event(
         self,
         event_id: str,
@@ -446,6 +448,7 @@ async def get_events(
 
     @trace
     @tag_args
+    @cancellable
     async def get_events_as_list(
         self,
         event_ids: Collection[str],
@@ -597,6 +600,7 @@ async def get_events_as_list(
 
         return events
 
+    @cancellable
     async def _get_events_from_cache_or_db(
         self, event_ids: Iterable[str], allow_rejected: bool = False
     ) -> Dict[str, EventCacheEntry]:
@@ -1169,7 +1173,7 @@ async def _fetch_event_ids_and_get_outstanding_redactions(
             if format_version is None:
                 # This means that we stored the event before we had the concept
                 # of a event format version, so it must be a V1 event.
-                format_version = EventFormatVersions.V1
+                format_version = EventFormatVersions.ROOM_V1_V2
 
             room_version_id = row.room_version_id
 
@@ -1199,10 +1203,10 @@ async def _fetch_event_ids_and_get_outstanding_redactions(
                 #
                 # So, the following approximations should be adequate.
 
-                if format_version == EventFormatVersions.V1:
+                if format_version == EventFormatVersions.ROOM_V1_V2:
                     # if it's event format v1 then it must be room v1 or v2
                     room_version = RoomVersions.V1
-                elif format_version == EventFormatVersions.V2:
+                elif format_version == EventFormatVersions.ROOM_V3:
                     # if it's event format v2 then it must be room v3
                     room_version = RoomVersions.V3
                 else:
diff --git a/synapse/storage/databases/main/lock.py b/synapse/storage/databases/main/lock.py
index 2d7633fbd5ed..7270ef09da9e 100644
--- a/synapse/storage/databases/main/lock.py
+++ b/synapse/storage/databases/main/lock.py
@@ -129,91 +129,48 @@ async def _try_acquire_lock(
         now = self._clock.time_msec()
         token = random_string(6)
 
-        if self.db_pool.engine.can_native_upsert:
-
-            def _try_acquire_lock_txn(txn: LoggingTransaction) -> bool:
-                # We take out the lock if either a) there is no row for the lock
-                # already, b) the existing row has timed out, or c) the row is
-                # for this instance (which means the process got killed and
-                # restarted)
-                sql = """
-                    INSERT INTO worker_locks (lock_name, lock_key, instance_name, token, last_renewed_ts)
-                    VALUES (?, ?, ?, ?, ?)
-                    ON CONFLICT (lock_name, lock_key)
-                    DO UPDATE
-                        SET
-                            token = EXCLUDED.token,
-                            instance_name = EXCLUDED.instance_name,
-                            last_renewed_ts = EXCLUDED.last_renewed_ts
-                        WHERE
-                            worker_locks.last_renewed_ts < ?
-                            OR worker_locks.instance_name = EXCLUDED.instance_name
-                """
-                txn.execute(
-                    sql,
-                    (
-                        lock_name,
-                        lock_key,
-                        self._instance_name,
-                        token,
-                        now,
-                        now - _LOCK_TIMEOUT_MS,
-                    ),
-                )
-
-                # We only acquired the lock if we inserted or updated the table.
-                return bool(txn.rowcount)
-
-            did_lock = await self.db_pool.runInteraction(
-                "try_acquire_lock",
-                _try_acquire_lock_txn,
-                # We can autocommit here as we're executing a single query, this
-                # will avoid serialization errors.
-                db_autocommit=True,
+        def _try_acquire_lock_txn(txn: LoggingTransaction) -> bool:
+            # We take out the lock if either a) there is no row for the lock
+            # already, b) the existing row has timed out, or c) the row is
+            # for this instance (which means the process got killed and
+            # restarted)
+            sql = """
+               INSERT INTO worker_locks (lock_name, lock_key, instance_name, token, last_renewed_ts)
+               VALUES (?, ?, ?, ?, ?)
+               ON CONFLICT (lock_name, lock_key)
+               DO UPDATE
+                   SET
+                       token = EXCLUDED.token,
+                       instance_name = EXCLUDED.instance_name,
+                       last_renewed_ts = EXCLUDED.last_renewed_ts
+                   WHERE
+                       worker_locks.last_renewed_ts < ?
+                       OR worker_locks.instance_name = EXCLUDED.instance_name
+           """
+            txn.execute(
+                sql,
+                (
+                    lock_name,
+                    lock_key,
+                    self._instance_name,
+                    token,
+                    now,
+                    now - _LOCK_TIMEOUT_MS,
+                ),
             )
-            if not did_lock:
-                return None
-
-        else:
-            # If we're on an old SQLite we emulate the above logic by first
-            # clearing out any existing stale locks and then upserting.
-
-            def _try_acquire_lock_emulated_txn(txn: LoggingTransaction) -> bool:
-                sql = """
-                    DELETE FROM worker_locks
-                    WHERE
-                        lock_name = ?
-                        AND lock_key = ?
-                        AND (last_renewed_ts < ? OR instance_name = ?)
-                """
-                txn.execute(
-                    sql,
-                    (lock_name, lock_key, now - _LOCK_TIMEOUT_MS, self._instance_name),
-                )
-
-                inserted = self.db_pool.simple_upsert_txn_emulated(
-                    txn,
-                    table="worker_locks",
-                    keyvalues={
-                        "lock_name": lock_name,
-                        "lock_key": lock_key,
-                    },
-                    values={},
-                    insertion_values={
-                        "token": token,
-                        "last_renewed_ts": self._clock.time_msec(),
-                        "instance_name": self._instance_name,
-                    },
-                )
-
-                return inserted
 
-            did_lock = await self.db_pool.runInteraction(
-                "try_acquire_lock_emulated", _try_acquire_lock_emulated_txn
-            )
+            # We only acquired the lock if we inserted or updated the table.
+            return bool(txn.rowcount)
 
-            if not did_lock:
-                return None
+        did_lock = await self.db_pool.runInteraction(
+            "try_acquire_lock",
+            _try_acquire_lock_txn,
+            # We can autocommit here as we're executing a single query, this
+            # will avoid serialization errors.
+            db_autocommit=True,
+        )
+        if not did_lock:
+            return None
 
         lock = Lock(
             self._reactor,
diff --git a/synapse/storage/databases/main/purge_events.py b/synapse/storage/databases/main/purge_events.py
index f6822707e43c..9213ce0b5abb 100644
--- a/synapse/storage/databases/main/purge_events.py
+++ b/synapse/storage/databases/main/purge_events.py
@@ -419,6 +419,7 @@ def _purge_room_txn(self, txn: LoggingTransaction, room_id: str) -> List[int]:
             "event_forward_extremities",
             "event_push_actions",
             "event_search",
+            "event_failed_pull_attempts",
             "partial_state_events",
             "events",
             "federation_inbound_events_staging",
@@ -441,6 +442,10 @@ def _purge_room_txn(self, txn: LoggingTransaction, room_id: str) -> List[int]:
             "e2e_room_keys",
             "event_push_summary",
             "pusher_throttle",
+            "insertion_events",
+            "insertion_event_extremities",
+            "insertion_event_edges",
+            "batch_events",
             "room_account_data",
             "room_tags",
             # "rooms" happens last, to keep the foreign keys in the other tables
diff --git a/synapse/storage/databases/main/receipts.py b/synapse/storage/databases/main/receipts.py
index c8fbee489957..eff0dd5a6671 100644
--- a/synapse/storage/databases/main/receipts.py
+++ b/synapse/storage/databases/main/receipts.py
@@ -115,6 +115,24 @@ def __init__(
             prefilled_cache=receipts_stream_prefill,
         )
 
+        self.db_pool.updates.register_background_index_update(
+            "receipts_linearized_unique_index",
+            index_name="receipts_linearized_unique_index",
+            table="receipts_linearized",
+            columns=["room_id", "receipt_type", "user_id"],
+            where_clause="thread_id IS NULL",
+            unique=True,
+        )
+
+        self.db_pool.updates.register_background_index_update(
+            "receipts_graph_unique_index",
+            index_name="receipts_graph_unique_index",
+            table="receipts_graph",
+            columns=["room_id", "receipt_type", "user_id"],
+            where_clause="thread_id IS NULL",
+            unique=True,
+        )
+
     def get_max_receipt_stream_id(self) -> int:
         """Get the current max stream ID for receipts stream"""
         return self._receipts_id_gen.get_current_token()
@@ -690,6 +708,7 @@ def _insert_linearized_receipt_txn(
                 "event_id": event_id,
                 "event_stream_ordering": stream_ordering,
                 "data": json_encoder.encode(data),
+                "thread_id": None,
             },
             # receipts_linearized has a unique constraint on
             # (user_id, room_id, receipt_type), so no need to lock
@@ -826,7 +845,7 @@ def _insert_graph_receipt_txn(
         # FIXME: This shouldn't invalidate the whole cache
         txn.call_after(self._get_linearized_receipts_for_room.invalidate, (room_id,))
 
-        self.db_pool.simple_delete_txn(
+        self.db_pool.simple_upsert_txn(
             txn,
             table="receipts_graph",
             keyvalues={
@@ -834,17 +853,14 @@ def _insert_graph_receipt_txn(
                 "receipt_type": receipt_type,
                 "user_id": user_id,
             },
-        )
-        self.db_pool.simple_insert_txn(
-            txn,
-            table="receipts_graph",
             values={
-                "room_id": room_id,
-                "receipt_type": receipt_type,
-                "user_id": user_id,
                 "event_ids": json_encoder.encode(event_ids),
                 "data": json_encoder.encode(data),
+                "thread_id": None,
             },
+            # receipts_graph has a unique constraint on
+            # (user_id, room_id, receipt_type), so no need to lock
+            lock=False,
         )
 
 
diff --git a/synapse/storage/databases/main/registration.py b/synapse/storage/databases/main/registration.py
index 7fb9c801dac8..ac821878b0ce 100644
--- a/synapse/storage/databases/main/registration.py
+++ b/synapse/storage/databases/main/registration.py
@@ -175,6 +175,7 @@ async def get_user_by_id(self, user_id: str) -> Optional[Dict[str, Any]]:
                 "is_guest",
                 "admin",
                 "consent_version",
+                "consent_ts",
                 "consent_server_notice_sent",
                 "appservice_id",
                 "creation_ts",
@@ -2227,7 +2228,10 @@ def f(txn: LoggingTransaction) -> None:
                 txn,
                 table="users",
                 keyvalues={"name": user_id},
-                updatevalues={"consent_version": consent_version},
+                updatevalues={
+                    "consent_version": consent_version,
+                    "consent_ts": self._clock.time_msec(),
+                },
             )
             self._invalidate_cache_and_stream(txn, self.get_user_by_id, (user_id,))
 
diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index 505c8d361165..30825b611613 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -32,10 +32,7 @@
 
 from synapse.api.constants import EventTypes, Membership
 from synapse.metrics import LaterGauge
-from synapse.metrics.background_process_metrics import (
-    run_as_background_process,
-    wrap_as_background_process,
-)
+from synapse.metrics.background_process_metrics import wrap_as_background_process
 from synapse.storage._base import SQLBaseStore, db_to_json, make_in_list_sql_clause
 from synapse.storage.database import (
     DatabasePool,
@@ -55,6 +52,7 @@
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import intern_string
 from synapse.util.caches.descriptors import _CacheContext, cached, cachedList
+from synapse.util.cancellation import cancellable
 from synapse.util.iterutils import batch_iter
 from synapse.util.metrics import Measure
 
@@ -90,15 +88,7 @@ def __init__(
         # at a time. Keyed by room_id.
         self._joined_host_linearizer = Linearizer("_JoinedHostsCache")
 
-        # Is the current_state_events.membership up to date? Or is the
-        # background update still running?
-        self._current_state_events_membership_up_to_date = False
-
-        txn = db_conn.cursor(
-            txn_name="_check_safe_current_state_events_membership_updated"
-        )
-        self._check_safe_current_state_events_membership_updated_txn(txn)
-        txn.close()
+        self._server_notices_mxid = hs.config.servernotices.server_notices_mxid
 
         if (
             self.hs.config.worker.run_background_tasks
@@ -156,34 +146,6 @@ def _transact(txn: LoggingTransaction) -> int:
         self._known_servers_count = max([count, 1])
         return self._known_servers_count
 
-    def _check_safe_current_state_events_membership_updated_txn(
-        self, txn: LoggingTransaction
-    ) -> None:
-        """Checks if it is safe to assume the new current_state_events
-        membership column is up to date
-        """
-
-        pending_update = self.db_pool.simple_select_one_txn(
-            txn,
-            table="background_updates",
-            keyvalues={"update_name": _CURRENT_STATE_MEMBERSHIP_UPDATE_NAME},
-            retcols=["update_name"],
-            allow_none=True,
-        )
-
-        self._current_state_events_membership_up_to_date = not pending_update
-
-        # If the update is still running, reschedule to run.
-        if pending_update:
-            self._clock.call_later(
-                15.0,
-                run_as_background_process,
-                "_check_safe_current_state_events_membership_updated",
-                self.db_pool.runInteraction,
-                "_check_safe_current_state_events_membership_updated",
-                self._check_safe_current_state_events_membership_updated_txn,
-            )
-
     @cached(max_entries=100000, iterable=True)
     async def get_users_in_room(self, room_id: str) -> List[str]:
         """
@@ -191,8 +153,15 @@ async def get_users_in_room(self, room_id: str) -> List[str]:
         (aka. with the lowest depth). This is done to match the sort in
         `get_current_hosts_in_room()` and so we can re-use the cache but it's
         not horrible to have here either.
-        """
 
+        Uses `m.room.member`s in the room state at the current forward extremities to
+        determine which users are in the room.
+
+        Will return inaccurate results for rooms with partial state, since the state for
+        the forward extremities of those rooms will exclude most members. We may also
+        calculate room state incorrectly for such rooms and believe that a member is or
+        is not in the room when the opposite is true.
+        """
         return await self.db_pool.runInteraction(
             "get_users_in_room", self.get_users_in_room_txn, room_id
         )
@@ -204,31 +173,14 @@ def get_users_in_room_txn(self, txn: LoggingTransaction, room_id: str) -> List[s
         `get_current_hosts_in_room()` and so we can re-use the cache but it's
         not horrible to have here either.
         """
-        # If we can assume current_state_events.membership is up to date
-        # then we can avoid a join, which is a Very Good Thing given how
-        # frequently this function gets called.
-        if self._current_state_events_membership_up_to_date:
-            sql = """
-                SELECT c.state_key FROM current_state_events as c
-                /* Get the depth of the event from the events table */
-                INNER JOIN events AS e USING (event_id)
-                WHERE c.type = 'm.room.member' AND c.room_id = ? AND membership = ?
-                /* Sorted by lowest depth first */
-                ORDER BY e.depth ASC;
-            """
-        else:
-            sql = """
-                SELECT c.state_key FROM room_memberships as m
-                /* Get the depth of the event from the events table */
-                INNER JOIN events AS e USING (event_id)
-                INNER JOIN current_state_events as c
-                ON m.event_id = c.event_id
-                AND m.room_id = c.room_id
-                AND m.user_id = c.state_key
-                WHERE c.type = 'm.room.member' AND c.room_id = ? AND m.membership = ?
-                /* Sorted by lowest depth first */
-                ORDER BY e.depth ASC;
-            """
+        sql = """
+            SELECT c.state_key FROM current_state_events as c
+            /* Get the depth of the event from the events table */
+            INNER JOIN events AS e USING (event_id)
+            WHERE c.type = 'm.room.member' AND c.room_id = ? AND membership = ?
+            /* Sorted by lowest depth first */
+            ORDER BY e.depth ASC;
+        """
 
         txn.execute(sql, (room_id, Membership.JOIN))
         return [r[0] for r in txn]
@@ -345,28 +297,14 @@ def _get_room_summary_txn(
             # We do this all in one transaction to keep the cache small.
             # FIXME: get rid of this when we have room_stats
 
-            # If we can assume current_state_events.membership is up to date
-            # then we can avoid a join, which is a Very Good Thing given how
-            # frequently this function gets called.
-            if self._current_state_events_membership_up_to_date:
-                # Note, rejected events will have a null membership field, so
-                # we we manually filter them out.
-                sql = """
-                    SELECT count(*), membership FROM current_state_events
-                    WHERE type = 'm.room.member' AND room_id = ?
-                        AND membership IS NOT NULL
-                    GROUP BY membership
-                """
-            else:
-                sql = """
-                    SELECT count(*), m.membership FROM room_memberships as m
-                    INNER JOIN current_state_events as c
-                    ON m.event_id = c.event_id
-                    AND m.room_id = c.room_id
-                    AND m.user_id = c.state_key
-                    WHERE c.type = 'm.room.member' AND c.room_id = ?
-                    GROUP BY m.membership
-                """
+            # Note, rejected events will have a null membership field, so
+            # we we manually filter them out.
+            sql = """
+                SELECT count(*), membership FROM current_state_events
+                WHERE type = 'm.room.member' AND room_id = ?
+                    AND membership IS NOT NULL
+                GROUP BY membership
+            """
 
             txn.execute(sql, (room_id,))
             res: Dict[str, MemberSummary] = {}
@@ -375,30 +313,18 @@ def _get_room_summary_txn(
 
             # we order by membership and then fairly arbitrarily by event_id so
             # heroes are consistent
-            if self._current_state_events_membership_up_to_date:
-                # Note, rejected events will have a null membership field, so
-                # we we manually filter them out.
-                sql = """
-                    SELECT state_key, membership, event_id
-                    FROM current_state_events
-                    WHERE type = 'm.room.member' AND room_id = ?
-                        AND membership IS NOT NULL
-                    ORDER BY
-                        CASE membership WHEN ? THEN 1 WHEN ? THEN 2 ELSE 3 END ASC,
-                        event_id ASC
-                    LIMIT ?
-                """
-            else:
-                sql = """
-                    SELECT c.state_key, m.membership, c.event_id
-                    FROM room_memberships as m
-                    INNER JOIN current_state_events as c USING (room_id, event_id)
-                    WHERE c.type = 'm.room.member' AND c.room_id = ?
-                    ORDER BY
-                        CASE m.membership WHEN ? THEN 1 WHEN ? THEN 2 ELSE 3 END ASC,
-                        c.event_id ASC
-                    LIMIT ?
-                """
+            # Note, rejected events will have a null membership field, so
+            # we we manually filter them out.
+            sql = """
+                SELECT state_key, membership, event_id
+                FROM current_state_events
+                WHERE type = 'm.room.member' AND room_id = ?
+                    AND membership IS NOT NULL
+                ORDER BY
+                    CASE membership WHEN ? THEN 1 WHEN ? THEN 2 ELSE 3 END ASC,
+                    event_id ASC
+                LIMIT ?
+            """
 
             # 6 is 5 (number of heroes) plus 1, in case one of them is the calling user.
             txn.execute(sql, (room_id, Membership.JOIN, Membership.INVITE, 6))
@@ -599,6 +525,21 @@ async def check_local_user_in_room(self, user_id: str, room_id: str) -> bool:
 
         return membership == Membership.JOIN
 
+    async def is_server_notice_room(self, room_id: str) -> bool:
+        """
+        Determines whether the given room is a 'Server Notices' room, used for
+        sending server notices to a user.
+
+        This is determined by seeing whether the server notices user is present
+        in the room.
+        """
+        if self._server_notices_mxid is None:
+            return False
+        is_server_notices_room = await self.check_local_user_in_room(
+            user_id=self._server_notices_mxid, room_id=room_id
+        )
+        return is_server_notices_room
+
     async def get_local_current_membership_for_user_in_room(
         self, user_id: str, room_id: str
     ) -> Tuple[Optional[str], Optional[str]]:
@@ -660,27 +601,15 @@ def _get_rooms_for_user_with_stream_ordering_txn(
         # We use `current_state_events` here and not `local_current_membership`
         # as a) this gets called with remote users and b) this only gets called
         # for rooms the server is participating in.
-        if self._current_state_events_membership_up_to_date:
-            sql = """
-                SELECT room_id, e.instance_name, e.stream_ordering
-                FROM current_state_events AS c
-                INNER JOIN events AS e USING (room_id, event_id)
-                WHERE
-                    c.type = 'm.room.member'
-                    AND c.state_key = ?
-                    AND c.membership = ?
-            """
-        else:
-            sql = """
-                SELECT room_id, e.instance_name, e.stream_ordering
-                FROM current_state_events AS c
-                INNER JOIN room_memberships AS m USING (room_id, event_id)
-                INNER JOIN events AS e USING (room_id, event_id)
-                WHERE
-                    c.type = 'm.room.member'
-                    AND c.state_key = ?
-                    AND m.membership = ?
-            """
+        sql = """
+            SELECT room_id, e.instance_name, e.stream_ordering
+            FROM current_state_events AS c
+            INNER JOIN events AS e USING (room_id, event_id)
+            WHERE
+                c.type = 'm.room.member'
+                AND c.state_key = ?
+                AND c.membership = ?
+        """
 
         txn.execute(sql, (user_id, Membership.JOIN))
         return frozenset(
@@ -718,27 +647,15 @@ def _get_rooms_for_users_with_stream_ordering_txn(
             user_ids,
         )
 
-        if self._current_state_events_membership_up_to_date:
-            sql = f"""
-                SELECT c.state_key, room_id, e.instance_name, e.stream_ordering
-                FROM current_state_events AS c
-                INNER JOIN events AS e USING (room_id, event_id)
-                WHERE
-                    c.type = 'm.room.member'
-                    AND c.membership = ?
-                    AND {clause}
-            """
-        else:
-            sql = f"""
-                SELECT c.state_key, room_id, e.instance_name, e.stream_ordering
-                FROM current_state_events AS c
-                INNER JOIN room_memberships AS m USING (room_id, event_id)
-                INNER JOIN events AS e USING (room_id, event_id)
-                WHERE
-                    c.type = 'm.room.member'
-                    AND m.membership = ?
-                    AND {clause}
-            """
+        sql = f"""
+            SELECT c.state_key, room_id, e.instance_name, e.stream_ordering
+            FROM current_state_events AS c
+            INNER JOIN events AS e USING (room_id, event_id)
+            WHERE
+                c.type = 'm.room.member'
+                AND c.membership = ?
+                AND {clause}
+        """
 
         txn.execute(sql, [Membership.JOIN] + args)
 
@@ -789,6 +706,7 @@ def _get_users_server_still_shares_room_with_txn(
             _get_users_server_still_shares_room_with_txn,
         )
 
+    @cancellable
     async def get_rooms_for_user(
         self, user_id: str, on_invalidate: Optional[Callable[[], None]] = None
     ) -> FrozenSet[str]:
@@ -1039,6 +957,14 @@ async def get_current_hosts_in_room(self, room_id: str) -> List[str]:
         longest is good because they're most likely to have anything we ask
         about.
 
+        Uses `m.room.member`s in the room state at the current forward extremities to
+        determine which hosts are in the room.
+
+        Will return inaccurate results for rooms with partial state, since the state for
+        the forward extremities of those rooms will exclude most members. We may also
+        calculate room state incorrectly for such rooms and believe that a host is or
+        is not in the room when the opposite is true.
+
         Returns:
             Returns a list of servers sorted by longest in the room first. (aka.
             sorted by join with the lowest depth first).
@@ -1061,6 +987,8 @@ async def get_current_hosts_in_room(self, room_id: str) -> List[str]:
             # We use a `Set` just for fast lookups
             domain_set: Set[str] = set()
             for u in users:
+                if ":" not in u:
+                    continue
                 domain = get_domain_from_id(u)
                 if domain not in domain_set:
                     domain_set.add(domain)
@@ -1094,7 +1022,8 @@ def get_current_hosts_in_room_txn(txn: LoggingTransaction) -> List[str]:
                 ORDER BY min(e.depth) ASC;
             """
             txn.execute(sql, (room_id,))
-            return [d for d, in txn]
+            # `server_domain` will be `NULL` for malformed MXIDs with no colons.
+            return [d for d, in txn if d is not None]
 
         return await self.db_pool.runInteraction(
             "get_current_hosts_in_room", get_current_hosts_in_room_txn
diff --git a/synapse/storage/databases/main/state.py b/synapse/storage/databases/main/state.py
index 0b10af0e580e..af7bebee8030 100644
--- a/synapse/storage/databases/main/state.py
+++ b/synapse/storage/databases/main/state.py
@@ -23,6 +23,7 @@
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion
 from synapse.events import EventBase
 from synapse.events.snapshot import EventContext
+from synapse.logging.opentracing import trace
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.database import (
     DatabasePool,
@@ -36,6 +37,7 @@
 from synapse.types import JsonDict, JsonMapping, StateMap
 from synapse.util.caches import intern_string
 from synapse.util.caches.descriptors import cached, cachedList
+from synapse.util.cancellation import cancellable
 from synapse.util.iterutils import batch_iter
 
 if TYPE_CHECKING:
@@ -142,6 +144,7 @@ def get_room_version_id_txn(self, txn: LoggingTransaction, room_id: str) -> str:
 
         return room_version
 
+    @trace
     async def get_metadata_for_events(
         self, event_ids: Collection[str]
     ) -> Dict[str, EventMetadata]:
@@ -281,6 +284,7 @@ def _get_current_state_ids_txn(txn: LoggingTransaction) -> StateMap[str]:
         )
 
     # FIXME: how should this be cached?
+    @cancellable
     async def get_partial_filtered_current_state_ids(
         self, room_id: str, state_filter: Optional[StateFilter] = None
     ) -> StateMap[str]:
diff --git a/synapse/storage/databases/main/stats.py b/synapse/storage/databases/main/stats.py
index b4c652acf34e..356d4ca78819 100644
--- a/synapse/storage/databases/main/stats.py
+++ b/synapse/storage/databases/main/stats.py
@@ -446,59 +446,41 @@ def _upsert_with_additive_relatives_txn(
             absolutes: Absolute (set) fields
             additive_relatives: Fields that will be added onto if existing row present.
         """
-        if self.database_engine.can_native_upsert:
-            absolute_updates = [
-                "%(field)s = EXCLUDED.%(field)s" % {"field": field}
-                for field in absolutes.keys()
-            ]
-
-            relative_updates = [
-                "%(field)s = EXCLUDED.%(field)s + COALESCE(%(table)s.%(field)s, 0)"
-                % {"table": table, "field": field}
-                for field in additive_relatives.keys()
-            ]
-
-            insert_cols = []
-            qargs = []
-
-            for (key, val) in chain(
-                keyvalues.items(), absolutes.items(), additive_relatives.items()
-            ):
-                insert_cols.append(key)
-                qargs.append(val)
+        absolute_updates = [
+            "%(field)s = EXCLUDED.%(field)s" % {"field": field}
+            for field in absolutes.keys()
+        ]
+
+        relative_updates = [
+            "%(field)s = EXCLUDED.%(field)s + COALESCE(%(table)s.%(field)s, 0)"
+            % {"table": table, "field": field}
+            for field in additive_relatives.keys()
+        ]
+
+        insert_cols = []
+        qargs = []
+
+        for (key, val) in chain(
+            keyvalues.items(), absolutes.items(), additive_relatives.items()
+        ):
+            insert_cols.append(key)
+            qargs.append(val)
+
+        sql = """
+            INSERT INTO %(table)s (%(insert_cols_cs)s)
+            VALUES (%(insert_vals_qs)s)
+            ON CONFLICT (%(key_columns)s) DO UPDATE SET %(updates)s
+        """ % {
+            "table": table,
+            "insert_cols_cs": ", ".join(insert_cols),
+            "insert_vals_qs": ", ".join(
+                ["?"] * (len(keyvalues) + len(absolutes) + len(additive_relatives))
+            ),
+            "key_columns": ", ".join(keyvalues),
+            "updates": ", ".join(chain(absolute_updates, relative_updates)),
+        }
 
-            sql = """
-                INSERT INTO %(table)s (%(insert_cols_cs)s)
-                VALUES (%(insert_vals_qs)s)
-                ON CONFLICT (%(key_columns)s) DO UPDATE SET %(updates)s
-            """ % {
-                "table": table,
-                "insert_cols_cs": ", ".join(insert_cols),
-                "insert_vals_qs": ", ".join(
-                    ["?"] * (len(keyvalues) + len(absolutes) + len(additive_relatives))
-                ),
-                "key_columns": ", ".join(keyvalues),
-                "updates": ", ".join(chain(absolute_updates, relative_updates)),
-            }
-
-            txn.execute(sql, qargs)
-        else:
-            self.database_engine.lock_table(txn, table)
-            retcols = list(chain(absolutes.keys(), additive_relatives.keys()))
-            current_row = self.db_pool.simple_select_one_txn(
-                txn, table, keyvalues, retcols, allow_none=True
-            )
-            if current_row is None:
-                merged_dict = {**keyvalues, **absolutes, **additive_relatives}
-                self.db_pool.simple_insert_txn(txn, table, merged_dict)
-            else:
-                for (key, val) in additive_relatives.items():
-                    if current_row[key] is None:
-                        current_row[key] = val
-                    else:
-                        current_row[key] += val
-                current_row.update(absolutes)
-                self.db_pool.simple_update_one_txn(txn, table, keyvalues, current_row)
+        txn.execute(sql, qargs)
 
     async def _calculate_and_set_initial_state_for_room(self, room_id: str) -> None:
         """Calculate and insert an entry into room_stats_current.
diff --git a/synapse/storage/databases/main/stream.py b/synapse/storage/databases/main/stream.py
index a347430aa7e3..3f9bfaeac5cb 100644
--- a/synapse/storage/databases/main/stream.py
+++ b/synapse/storage/databases/main/stream.py
@@ -72,6 +72,7 @@
 from synapse.types import PersistedEventPosition, RoomStreamToken
 from synapse.util.caches.descriptors import cached
 from synapse.util.caches.stream_change_cache import StreamChangeCache
+from synapse.util.cancellation import cancellable
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -597,6 +598,7 @@ def f(txn: LoggingTransaction) -> List[_EventDictReturn]:
 
         return ret, key
 
+    @cancellable
     async def get_membership_changes_for_user(
         self,
         user_id: str,
diff --git a/synapse/storage/databases/main/transactions.py b/synapse/storage/databases/main/transactions.py
index ba79e19f7fe8..f8c6877ee847 100644
--- a/synapse/storage/databases/main/transactions.py
+++ b/synapse/storage/databases/main/transactions.py
@@ -221,25 +221,15 @@ async def set_destination_retry_timings(
             retry_interval: how long until next retry in ms
         """
 
-        if self.database_engine.can_native_upsert:
-            await self.db_pool.runInteraction(
-                "set_destination_retry_timings",
-                self._set_destination_retry_timings_native,
-                destination,
-                failure_ts,
-                retry_last_ts,
-                retry_interval,
-                db_autocommit=True,  # Safe as its a single upsert
-            )
-        else:
-            await self.db_pool.runInteraction(
-                "set_destination_retry_timings",
-                self._set_destination_retry_timings_emulated,
-                destination,
-                failure_ts,
-                retry_last_ts,
-                retry_interval,
-            )
+        await self.db_pool.runInteraction(
+            "set_destination_retry_timings",
+            self._set_destination_retry_timings_native,
+            destination,
+            failure_ts,
+            retry_last_ts,
+            retry_interval,
+            db_autocommit=True,  # Safe as it's a single upsert
+        )
 
     def _set_destination_retry_timings_native(
         self,
@@ -249,8 +239,6 @@ def _set_destination_retry_timings_native(
         retry_last_ts: int,
         retry_interval: int,
     ) -> None:
-        assert self.database_engine.can_native_upsert
-
         # Upsert retry time interval if retry_interval is zero (i.e. we're
         # resetting it) or greater than the existing retry interval.
         #
diff --git a/synapse/storage/databases/state/store.py b/synapse/storage/databases/state/store.py
index bb64543c1f2d..f8cfcaca83e1 100644
--- a/synapse/storage/databases/state/store.py
+++ b/synapse/storage/databases/state/store.py
@@ -31,6 +31,7 @@
 from synapse.types import MutableStateMap, StateKey, StateMap
 from synapse.util.caches.descriptors import cached
 from synapse.util.caches.dictionary_cache import DictionaryCache
+from synapse.util.cancellation import cancellable
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -156,6 +157,7 @@ def _get_state_group_delta_txn(txn: LoggingTransaction) -> _GetStateGroupDelta:
             "get_state_group_delta", _get_state_group_delta_txn
         )
 
+    @cancellable
     async def _get_state_groups_from_groups(
         self, groups: List[int], state_filter: StateFilter
     ) -> Dict[int, StateMap[str]]:
@@ -235,6 +237,7 @@ def _get_state_for_group_using_cache(
 
         return state_filter.filter_state(state_dict_ids), not missing_types
 
+    @cancellable
     async def _get_state_for_groups(
         self, groups: Iterable[int], state_filter: Optional[StateFilter] = None
     ) -> Dict[int, MutableStateMap[str]]:
diff --git a/synapse/storage/engines/_base.py b/synapse/storage/engines/_base.py
index 971ff8269323..0d16a419a42c 100644
--- a/synapse/storage/engines/_base.py
+++ b/synapse/storage/engines/_base.py
@@ -43,14 +43,6 @@ def __init__(self, module: DBAPI2Module, config: Mapping[str, Any]):
     def single_threaded(self) -> bool:
         ...
 
-    @property
-    @abc.abstractmethod
-    def can_native_upsert(self) -> bool:
-        """
-        Do we support native UPSERTs?
-        """
-        ...
-
     @property
     @abc.abstractmethod
     def supports_using_any_list(self) -> bool:
diff --git a/synapse/storage/engines/postgres.py b/synapse/storage/engines/postgres.py
index 517f9d5f98d7..7f7d006ac209 100644
--- a/synapse/storage/engines/postgres.py
+++ b/synapse/storage/engines/postgres.py
@@ -158,13 +158,6 @@ def on_new_connection(self, db_conn: "LoggingDatabaseConnection") -> None:
         cursor.close()
         db_conn.commit()
 
-    @property
-    def can_native_upsert(self) -> bool:
-        """
-        Can we use native UPSERTs?
-        """
-        return True
-
     @property
     def supports_using_any_list(self) -> bool:
         """Do we support using `a = ANY(?)` and passing a list"""
diff --git a/synapse/storage/engines/sqlite.py b/synapse/storage/engines/sqlite.py
index 621f2c5efe28..095ae0a096b8 100644
--- a/synapse/storage/engines/sqlite.py
+++ b/synapse/storage/engines/sqlite.py
@@ -48,14 +48,6 @@ def __init__(self, database_config: Mapping[str, Any]):
     def single_threaded(self) -> bool:
         return True
 
-    @property
-    def can_native_upsert(self) -> bool:
-        """
-        Do we support native UPSERTs? This requires SQLite3 3.24+, plus some
-        more work we haven't done yet to tell what was inserted vs updated.
-        """
-        return sqlite3.sqlite_version_info >= (3, 24, 0)
-
     @property
     def supports_using_any_list(self) -> bool:
         """Do we support using `a = ANY(?)` and passing a list"""
@@ -70,12 +62,11 @@ def check_database(
         self, db_conn: sqlite3.Connection, allow_outdated_version: bool = False
     ) -> None:
         if not allow_outdated_version:
-            version = sqlite3.sqlite_version_info
             # Synapse is untested against older SQLite versions, and we don't want
             # to let users upgrade to a version of Synapse with broken support for their
             # sqlite version, because it risks leaving them with a half-upgraded db.
-            if version < (3, 22, 0):
-                raise RuntimeError("Synapse requires sqlite 3.22 or above.")
+            if sqlite3.sqlite_version_info < (3, 27, 0):
+                raise RuntimeError("Synapse requires sqlite 3.27 or above.")
 
     def check_new_database(self, txn: Cursor) -> None:
         """Gets called when setting up a brand new database. This allows us to
diff --git a/synapse/storage/schema/__init__.py b/synapse/storage/schema/__init__.py
index 256f745dc0e8..f29424d17a74 100644
--- a/synapse/storage/schema/__init__.py
+++ b/synapse/storage/schema/__init__.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-SCHEMA_VERSION = 72  # remember to update the list below when updating
+SCHEMA_VERSION = 73  # remember to update the list below when updating
 """Represents the expectations made by the codebase about the database schema
 
 This should be incremented whenever the codebase changes its requirements on the
@@ -76,6 +76,15 @@
     - event_edges.(room_id, is_state) are no longer written to.
     - Tables related to groups are dropped.
     - Unused column application_services_state.last_txn is dropped
+    - Cache invalidation stream id sequence now begins at 2 to match code expectation.
+
+Changes in SCHEMA_VERSION = 73;
+    - thread_id column is added to event_push_actions, event_push_actions_staging
+      event_push_summary, receipts_linearized, and receipts_graph.
+    - Add table `event_failed_pull_attempts` to keep track when we fail to pull
+      events over federation.
+    - Add indexes to various tables (`event_failed_pull_attempts`, `insertion_events`,
+      `batch_events`) to make it easy to delete all associated rows when purging a room.
 """
 
 
diff --git a/synapse/storage/schema/main/delta/72/06add_consent_ts_to_users.sql b/synapse/storage/schema/main/delta/72/06add_consent_ts_to_users.sql
new file mode 100644
index 000000000000..609eb1750fd6
--- /dev/null
+++ b/synapse/storage/schema/main/delta/72/06add_consent_ts_to_users.sql
@@ -0,0 +1,16 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+ALTER TABLE users ADD consent_ts bigint;
diff --git a/synapse/storage/schema/main/delta/72/06thread_notifications.sql b/synapse/storage/schema/main/delta/72/06thread_notifications.sql
new file mode 100644
index 000000000000..2f4f5dac7a04
--- /dev/null
+++ b/synapse/storage/schema/main/delta/72/06thread_notifications.sql
@@ -0,0 +1,30 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+-- Add a nullable column for thread ID to the event push actions tables; this
+-- will be filled in with a default value for any previously existing rows.
+--
+-- After migration this can be made non-nullable.
+
+ALTER TABLE event_push_actions_staging ADD COLUMN thread_id TEXT;
+ALTER TABLE event_push_actions ADD COLUMN thread_id TEXT;
+ALTER TABLE event_push_summary ADD COLUMN thread_id TEXT;
+
+-- Update the unique index for `event_push_summary`.
+INSERT INTO background_updates (ordering, update_name, progress_json) VALUES
+  (7006, 'event_push_summary_unique_index2', '{}');
+
+INSERT INTO background_updates (ordering, update_name, progress_json, depends_on) VALUES
+  (7006, 'event_push_backfill_thread_id', '{}', 'event_push_summary_unique_index2');
diff --git a/synapse/storage/schema/main/delta/72/07force_update_current_state_events_membership.py b/synapse/storage/schema/main/delta/72/07force_update_current_state_events_membership.py
new file mode 100644
index 000000000000..b5853d125c6a
--- /dev/null
+++ b/synapse/storage/schema/main/delta/72/07force_update_current_state_events_membership.py
@@ -0,0 +1,52 @@
+# Copyright 2022 Beeper
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""
+Forces through the `current_state_events_membership` background job so checks
+for its completion can be removed.
+
+Note the background job must still remain defined in the database class.
+"""
+
+
+def run_upgrade(cur, database_engine, *args, **kwargs):
+    cur.execute("SELECT update_name FROM background_updates")
+    rows = cur.fetchall()
+    for row in rows:
+        if row[0] == "current_state_events_membership":
+            break
+    # No pending background job so nothing to do here
+    else:
+        return
+
+    # Populate membership field for all current_state_events, this may take
+    # a while but was originally handled via a background update in 2019.
+    cur.execute(
+        """
+        UPDATE current_state_events
+        SET membership = (
+            SELECT membership FROM room_memberships
+            WHERE event_id = current_state_events.event_id
+        )
+        """
+    )
+
+    # Finally, delete the background job because we've handled it above
+    cur.execute(
+        """
+        DELETE FROM background_updates
+        WHERE update_name = 'current_state_events_membership'
+        """
+    )
diff --git a/synapse/storage/schema/main/delta/72/07thread_receipts.sql.postgres b/synapse/storage/schema/main/delta/72/07thread_receipts.sql.postgres
new file mode 100644
index 000000000000..55fff9e278e7
--- /dev/null
+++ b/synapse/storage/schema/main/delta/72/07thread_receipts.sql.postgres
@@ -0,0 +1,30 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+-- Add a nullable column for thread ID to the receipts table; this allows a
+-- receipt per user, per room, as well as an unthreaded receipt (corresponding
+-- to a null thread ID).
+
+ALTER TABLE receipts_linearized ADD COLUMN thread_id TEXT;
+ALTER TABLE receipts_graph ADD COLUMN thread_id TEXT;
+
+-- Rebuild the unique constraint with the thread_id.
+ALTER TABLE receipts_linearized
+    ADD CONSTRAINT receipts_linearized_uniqueness_thread
+        UNIQUE (room_id, receipt_type, user_id, thread_id);
+
+ALTER TABLE receipts_graph
+    ADD CONSTRAINT receipts_graph_uniqueness_thread
+        UNIQUE (room_id, receipt_type, user_id, thread_id);
diff --git a/synapse/storage/schema/main/delta/72/07thread_receipts.sql.sqlite b/synapse/storage/schema/main/delta/72/07thread_receipts.sql.sqlite
new file mode 100644
index 000000000000..232f67deb4ac
--- /dev/null
+++ b/synapse/storage/schema/main/delta/72/07thread_receipts.sql.sqlite
@@ -0,0 +1,70 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+-- Allow multiple receipts per user per room via a nullable thread_id column.
+--
+-- SQLite doesn't support modifying constraints to an existing table, so it must
+-- be recreated.
+
+-- Create the new tables.
+CREATE TABLE receipts_linearized_new (
+    stream_id BIGINT NOT NULL,
+    room_id TEXT NOT NULL,
+    receipt_type TEXT NOT NULL,
+    user_id TEXT NOT NULL,
+    event_id TEXT NOT NULL,
+    thread_id TEXT,
+    event_stream_ordering BIGINT,
+    data TEXT NOT NULL,
+    CONSTRAINT receipts_linearized_uniqueness UNIQUE (room_id, receipt_type, user_id),
+    CONSTRAINT receipts_linearized_uniqueness_thread UNIQUE (room_id, receipt_type, user_id, thread_id)
+);
+
+CREATE TABLE receipts_graph_new (
+    room_id TEXT NOT NULL,
+    receipt_type TEXT NOT NULL,
+    user_id TEXT NOT NULL,
+    event_ids TEXT NOT NULL,
+    thread_id TEXT,
+    data TEXT NOT NULL,
+    CONSTRAINT receipts_graph_uniqueness UNIQUE (room_id, receipt_type, user_id),
+    CONSTRAINT receipts_graph_uniqueness_thread UNIQUE (room_id, receipt_type, user_id, thread_id)
+);
+
+-- Drop the old indexes.
+DROP INDEX IF EXISTS receipts_linearized_id;
+DROP INDEX IF EXISTS receipts_linearized_room_stream;
+DROP INDEX IF EXISTS receipts_linearized_user;
+
+-- Copy the data.
+INSERT INTO receipts_linearized_new (stream_id, room_id, receipt_type, user_id, event_id, event_stream_ordering, data)
+    SELECT stream_id, room_id, receipt_type, user_id, event_id, event_stream_ordering, data
+    FROM receipts_linearized;
+INSERT INTO receipts_graph_new (room_id, receipt_type, user_id, event_ids, data)
+    SELECT room_id, receipt_type, user_id, event_ids, data
+    FROM receipts_graph;
+
+-- Drop the old tables.
+DROP TABLE receipts_linearized;
+DROP TABLE receipts_graph;
+
+-- Rename the tables.
+ALTER TABLE receipts_linearized_new RENAME TO receipts_linearized;
+ALTER TABLE receipts_graph_new RENAME TO receipts_graph;
+
+-- Create the indices.
+CREATE INDEX receipts_linearized_id ON receipts_linearized( stream_id );
+CREATE INDEX receipts_linearized_room_stream ON receipts_linearized( room_id, stream_id );
+CREATE INDEX receipts_linearized_user ON receipts_linearized( user_id );
diff --git a/synapse/storage/schema/main/delta/72/08begin_cache_invalidation_seq_at_2.sql.postgres b/synapse/storage/schema/main/delta/72/08begin_cache_invalidation_seq_at_2.sql.postgres
new file mode 100644
index 000000000000..69931fe97195
--- /dev/null
+++ b/synapse/storage/schema/main/delta/72/08begin_cache_invalidation_seq_at_2.sql.postgres
@@ -0,0 +1,23 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+ 
+
+-- The sequence needs to begin at 2 because a bunch of code assumes that
+-- get_next_id_txn will return values >= 2, cf this comment:
+-- https://github.com/matrix-org/synapse/blob/b93bd95e8ab64d27ae26841020f62ee61272a5f2/synapse/storage/util/id_generators.py#L344
+
+SELECT setval('cache_invalidation_stream_seq', (
+    SELECT COALESCE(MAX(last_value), 1) FROM cache_invalidation_stream_seq
+));
diff --git a/synapse/storage/schema/main/delta/72/08thread_receipts.sql b/synapse/storage/schema/main/delta/72/08thread_receipts.sql
new file mode 100644
index 000000000000..e35b021f316a
--- /dev/null
+++ b/synapse/storage/schema/main/delta/72/08thread_receipts.sql
@@ -0,0 +1,20 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+INSERT INTO background_updates (ordering, update_name, progress_json) VALUES
+  (7007, 'receipts_linearized_unique_index', '{}');
+
+INSERT INTO background_updates (ordering, update_name, progress_json) VALUES
+  (7007, 'receipts_graph_unique_index', '{}');
diff --git a/synapse/storage/schema/main/delta/72/09partial_indices.sql.sqlite b/synapse/storage/schema/main/delta/72/09partial_indices.sql.sqlite
new file mode 100644
index 000000000000..c8dfdf02183d
--- /dev/null
+++ b/synapse/storage/schema/main/delta/72/09partial_indices.sql.sqlite
@@ -0,0 +1,56 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+ 
+-- SQLite needs to rebuild indices which use partial indices on Postgres, but
+-- previously did not use them on SQLite.
+
+-- Drop each index that was added with register_background_index_update AND specified
+-- a where_clause (that existed before this delta).
+
+-- From events_bg_updates.py
+DROP INDEX IF EXISTS event_contains_url_index;
+-- There is also a redactions_censored_redacts index, but that gets dropped.
+DROP INDEX IF EXISTS redactions_have_censored_ts;
+-- There is also a PostgreSQL only index (event_contains_url_index2)
+-- which gets renamed to event_contains_url_index.
+
+-- From roommember.py
+DROP INDEX IF EXISTS room_memberships_user_room_forgotten;
+
+-- From presence.py
+DROP INDEX IF EXISTS presence_stream_state_not_offline_idx;
+
+-- From media_repository.py
+DROP INDEX IF EXISTS local_media_repository_url_idx;
+
+-- From event_push_actions.py
+DROP INDEX IF EXISTS event_push_actions_highlights_index;
+-- There's also a event_push_actions_stream_highlight_index which was previously
+-- PostgreSQL-only.
+
+-- From state.py
+DROP INDEX IF EXISTS current_state_events_member_index;
+
+-- Re-insert the background jobs to re-create the indices.
+INSERT INTO background_updates (ordering, update_name, progress_json, depends_on) VALUES
+  (7209, 'event_contains_url_index', '{}', NULL),
+  (7209, 'redactions_have_censored_ts_idx', '{}', NULL),
+  (7209, 'room_membership_forgotten_idx', '{}', NULL),
+  (7209, 'presence_stream_not_offline_index', '{}', NULL),
+  (7209, 'local_media_repository_url_idx', '{}', NULL),
+  (7209, 'event_push_actions_highlights_index', '{}', NULL),
+  (7209, 'event_push_actions_stream_highlight_index', '{}', NULL),
+  (7209, 'current_state_members_idx', '{}', NULL)
+ON CONFLICT (update_name) DO NOTHING;
diff --git a/synapse/storage/schema/main/delta/73/01event_failed_pull_attempts.sql b/synapse/storage/schema/main/delta/73/01event_failed_pull_attempts.sql
new file mode 100644
index 000000000000..d397ee10826d
--- /dev/null
+++ b/synapse/storage/schema/main/delta/73/01event_failed_pull_attempts.sql
@@ -0,0 +1,29 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+-- Add a table that keeps track of when we failed to pull an event over
+-- federation (via /backfill, `/event`, `/get_missing_events`, etc). This allows
+-- us to be more intelligent when we decide to retry (we don't need to fail over
+-- and over) and we can process that event in the background so we don't block
+-- on it each time.
+CREATE TABLE IF NOT EXISTS event_failed_pull_attempts(
+    room_id TEXT NOT NULL REFERENCES rooms (room_id),
+    event_id TEXT NOT NULL,
+    num_attempts INT NOT NULL,
+    last_attempt_ts BIGINT NOT NULL,
+    last_cause TEXT NOT NULL,
+    PRIMARY KEY (room_id, event_id)
+);
diff --git a/synapse/storage/schema/main/delta/73/02room_id_indexes_for_purging.sql b/synapse/storage/schema/main/delta/73/02room_id_indexes_for_purging.sql
new file mode 100644
index 000000000000..6d38bdd43034
--- /dev/null
+++ b/synapse/storage/schema/main/delta/73/02room_id_indexes_for_purging.sql
@@ -0,0 +1,22 @@
+/* Copyright 2022 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+-- Add index so we can easily purge all rows from a given `room_id`
+CREATE INDEX IF NOT EXISTS event_failed_pull_attempts_room_id ON event_failed_pull_attempts(room_id);
+
+-- MSC2716 related tables:
+-- Add indexes so we can easily purge all rows from a given `room_id`
+CREATE INDEX IF NOT EXISTS insertion_events_room_id ON insertion_events(room_id);
+CREATE INDEX IF NOT EXISTS batch_events_room_id ON batch_events(room_id);
diff --git a/synapse/storage/schema/state/delta/30/state_stream.sql b/synapse/storage/schema/state/delta/30/state_stream.sql
deleted file mode 100644
index e85699e82e01..000000000000
--- a/synapse/storage/schema/state/delta/30/state_stream.sql
+++ /dev/null
@@ -1,33 +0,0 @@
-/* Copyright 2016 OpenMarket Ltd
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-
-/* We used to create a table called current_state_resets, but this is no
- * longer used and is removed in delta 54.
- */
-
-/* The outlier events that have aquired a state group typically through
- * backfill. This is tracked separately to the events table, as assigning a
- * state group change the position of the existing event in the stream
- * ordering.
- * However since a stream_ordering is assigned in persist_event for the
- * (event, state) pair, we can use that stream_ordering to identify when
- * the new state was assigned for the event.
- */
-CREATE TABLE IF NOT EXISTS ex_outlier_stream(
-    event_stream_ordering BIGINT PRIMARY KEY NOT NULL,
-    event_id TEXT NOT NULL,
-    state_group BIGINT NOT NULL
-);
diff --git a/synapse/storage/util/partial_state_events_tracker.py b/synapse/storage/util/partial_state_events_tracker.py
index b4bf49dace21..8d8894d1d585 100644
--- a/synapse/storage/util/partial_state_events_tracker.py
+++ b/synapse/storage/util/partial_state_events_tracker.py
@@ -24,6 +24,7 @@
 from synapse.storage.databases.main.events_worker import EventsWorkerStore
 from synapse.storage.databases.main.room import RoomWorkerStore
 from synapse.util import unwrapFirstError
+from synapse.util.cancellation import cancellable
 
 logger = logging.getLogger(__name__)
 
@@ -60,6 +61,7 @@ def notify_un_partial_stated(self, event_id: str) -> None:
                 o.callback(None)
 
     @trace_with_opname("PartialStateEventsTracker.await_full_state")
+    @cancellable
     async def await_full_state(self, event_ids: Collection[str]) -> None:
         """Wait for all the given events to have full state.
 
@@ -154,6 +156,7 @@ def notify_un_partial_stated(self, room_id: str) -> None:
                 o.callback(None)
 
     @trace_with_opname("PartialCurrentStateTracker.await_full_state")
+    @cancellable
     async def await_full_state(self, room_id: str) -> None:
         # We add the deferred immediately so that the DB call to check for
         # partial state doesn't race when we unpartial the room.
diff --git a/synapse/types.py b/synapse/types.py
index 668d48d646ae..ec44601f5424 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -52,6 +52,7 @@
 )
 
 from synapse.api.errors import Codes, SynapseError
+from synapse.util.cancellation import cancellable
 from synapse.util.stringutils import parse_and_validate_server_name
 
 if TYPE_CHECKING:
@@ -699,7 +700,11 @@ class StreamToken:
     START: ClassVar["StreamToken"]
 
     @classmethod
+    @cancellable
     async def from_string(cls, store: "DataStore", string: str) -> "StreamToken":
+        """
+        Creates a RoomStreamToken from its textual representation.
+        """
         try:
             keys = string.split(cls._SEPARATOR)
             while len(keys) < len(attr.fields(cls)):
diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index bdf9b0dc8cf7..f7c3a6794ed0 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -20,9 +20,11 @@
 from typing import Any, Callable, Dict, List, Optional, Sized, TypeVar
 
 import attr
+from prometheus_client import REGISTRY
 from prometheus_client.core import Gauge
 
 from synapse.config.cache import add_resizable_cache
+from synapse.util.metrics import DynamicCollectorRegistry
 
 logger = logging.getLogger(__name__)
 
@@ -30,27 +32,62 @@
 # Whether to track estimated memory usage of the LruCaches.
 TRACK_MEMORY_USAGE = False
 
+# We track cache metrics in a special registry that lets us update the metrics
+# just before they are returned from the scrape endpoint.
+CACHE_METRIC_REGISTRY = DynamicCollectorRegistry()
 
 caches_by_name: Dict[str, Sized] = {}
-collectors_by_name: Dict[str, "CacheMetric"] = {}
 
-cache_size = Gauge("synapse_util_caches_cache_size", "", ["name"])
-cache_hits = Gauge("synapse_util_caches_cache_hits", "", ["name"])
-cache_evicted = Gauge("synapse_util_caches_cache_evicted_size", "", ["name", "reason"])
-cache_total = Gauge("synapse_util_caches_cache_total", "", ["name"])
-cache_max_size = Gauge("synapse_util_caches_cache_max_size", "", ["name"])
+cache_size = Gauge(
+    "synapse_util_caches_cache_size", "", ["name"], registry=CACHE_METRIC_REGISTRY
+)
+cache_hits = Gauge(
+    "synapse_util_caches_cache_hits", "", ["name"], registry=CACHE_METRIC_REGISTRY
+)
+cache_evicted = Gauge(
+    "synapse_util_caches_cache_evicted_size",
+    "",
+    ["name", "reason"],
+    registry=CACHE_METRIC_REGISTRY,
+)
+cache_total = Gauge(
+    "synapse_util_caches_cache", "", ["name"], registry=CACHE_METRIC_REGISTRY
+)
+cache_max_size = Gauge(
+    "synapse_util_caches_cache_max_size", "", ["name"], registry=CACHE_METRIC_REGISTRY
+)
 cache_memory_usage = Gauge(
     "synapse_util_caches_cache_size_bytes",
     "Estimated memory usage of the caches",
     ["name"],
+    registry=CACHE_METRIC_REGISTRY,
 )
 
-response_cache_size = Gauge("synapse_util_caches_response_cache_size", "", ["name"])
-response_cache_hits = Gauge("synapse_util_caches_response_cache_hits", "", ["name"])
+response_cache_size = Gauge(
+    "synapse_util_caches_response_cache_size",
+    "",
+    ["name"],
+    registry=CACHE_METRIC_REGISTRY,
+)
+response_cache_hits = Gauge(
+    "synapse_util_caches_response_cache_hits",
+    "",
+    ["name"],
+    registry=CACHE_METRIC_REGISTRY,
+)
 response_cache_evicted = Gauge(
-    "synapse_util_caches_response_cache_evicted_size", "", ["name", "reason"]
+    "synapse_util_caches_response_cache_evicted_size",
+    "",
+    ["name", "reason"],
+    registry=CACHE_METRIC_REGISTRY,
 )
-response_cache_total = Gauge("synapse_util_caches_response_cache_total", "", ["name"])
+response_cache_total = Gauge(
+    "synapse_util_caches_response_cache", "", ["name"], registry=CACHE_METRIC_REGISTRY
+)
+
+
+# Register our custom cache metrics registry with the global registry
+REGISTRY.register(CACHE_METRIC_REGISTRY)
 
 
 class EvictionReason(Enum):
@@ -170,7 +207,7 @@ def register_cache(
     metric = CacheMetric(cache, cache_type, cache_name, collect_callback)
     metric_name = "cache_%s_%s" % (cache_type, cache_name)
     caches_by_name[cache_name] = cache
-    collectors_by_name[metric_name] = metric
+    CACHE_METRIC_REGISTRY.register_hook(metric_name, metric.collect)
     return metric
 
 
diff --git a/synapse/util/metrics.py b/synapse/util/metrics.py
index bc3b4938ea15..165480bdbef7 100644
--- a/synapse/util/metrics.py
+++ b/synapse/util/metrics.py
@@ -15,9 +15,9 @@
 import logging
 from functools import wraps
 from types import TracebackType
-from typing import Awaitable, Callable, Optional, Type, TypeVar
+from typing import Awaitable, Callable, Dict, Generator, Optional, Type, TypeVar
 
-from prometheus_client import Counter
+from prometheus_client import CollectorRegistry, Counter, Metric
 from typing_extensions import Concatenate, ParamSpec, Protocol
 
 from synapse.logging.context import (
@@ -208,3 +208,33 @@ def _update_in_flight(self, metrics: _InFlightMetric) -> None:
         metrics.real_time_sum += duration
 
         # TODO: Add other in flight metrics.
+
+
+class DynamicCollectorRegistry(CollectorRegistry):
+    """
+    Custom Prometheus Collector registry that calls a hook first, allowing you
+    to update metrics on-demand.
+
+    Don't forget to register this registry with the main registry!
+    """
+
+    def __init__(self) -> None:
+        super().__init__()
+        self._pre_update_hooks: Dict[str, Callable[[], None]] = {}
+
+    def collect(self) -> Generator[Metric, None, None]:
+        """
+        Collects metrics, calling pre-update hooks first.
+        """
+
+        for pre_update_hook in self._pre_update_hooks.values():
+            pre_update_hook()
+
+        yield from super().collect()
+
+    def register_hook(self, metric_name: str, hook: Callable[[], None]) -> None:
+        """
+        Registers a hook that is called before metric collection.
+        """
+
+        self._pre_update_hooks[metric_name] = hook
diff --git a/synapse/util/rust.py b/synapse/util/rust.py
new file mode 100644
index 000000000000..30ecb9ffd96d
--- /dev/null
+++ b/synapse/util/rust.py
@@ -0,0 +1,84 @@
+# Copyright 2022 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import sys
+from hashlib import blake2b
+
+import synapse
+from synapse.synapse_rust import get_rust_file_digest
+
+
+def check_rust_lib_up_to_date() -> None:
+    """For editable installs check if the rust library is outdated and needs to
+    be rebuilt.
+    """
+
+    if not _dist_is_editable():
+        return
+
+    synapse_dir = os.path.dirname(synapse.__file__)
+    synapse_root = os.path.abspath(os.path.join(synapse_dir, ".."))
+
+    # Double check we've not gone into site-packages...
+    if os.path.basename(synapse_root) == "site-packages":
+        return
+
+    # ... and it looks like the root of a python project.
+    if not os.path.exists("pyproject.toml"):
+        return
+
+    # Get the hash of all Rust source files
+    hash = _hash_rust_files_in_directory(os.path.join(synapse_root, "rust", "src"))
+
+    if hash != get_rust_file_digest():
+        raise Exception("Rust module outdated. Please rebuild using `poetry install`")
+
+
+def _hash_rust_files_in_directory(directory: str) -> str:
+    """Get the hash of all files in a directory (recursively)"""
+
+    directory = os.path.abspath(directory)
+
+    paths = []
+
+    dirs = [directory]
+    while dirs:
+        dir = dirs.pop()
+        with os.scandir(dir) as d:
+            for entry in d:
+                if entry.is_dir():
+                    dirs.append(entry.path)
+                else:
+                    paths.append(entry.path)
+
+    # We sort to make sure that we get a consistent and well-defined ordering.
+    paths.sort()
+
+    hasher = blake2b()
+
+    for path in paths:
+        with open(os.path.join(directory, path), "rb") as f:
+            hasher.update(f.read())
+
+    return hasher.hexdigest()
+
+
+def _dist_is_editable() -> bool:
+    """Is distribution an editable install?"""
+    for path_item in sys.path:
+        egg_link = os.path.join(path_item, "matrix-synapse.egg-link")
+        if os.path.isfile(egg_link):
+            return True
+    return False
diff --git a/tests/handlers/test_e2e_keys.py b/tests/handlers/test_e2e_keys.py
index 1e6ad4b663e9..95698bc27585 100644
--- a/tests/handlers/test_e2e_keys.py
+++ b/tests/handlers/test_e2e_keys.py
@@ -891,6 +891,12 @@ def test_query_all_devices_caches_result(self, device_ids: Iterable[str]) -> Non
             new_callable=mock.MagicMock,
             return_value=make_awaitable(["some_room_id"]),
         )
+        mock_get_users = mock.patch.object(
+            self.store,
+            "get_users_server_still_shares_room_with",
+            new_callable=mock.MagicMock,
+            return_value=make_awaitable({remote_user_id}),
+        )
         mock_request = mock.patch.object(
             self.hs.get_federation_client(),
             "query_user_devices",
@@ -898,7 +904,7 @@ def test_query_all_devices_caches_result(self, device_ids: Iterable[str]) -> Non
             return_value=make_awaitable(response_body),
         )
 
-        with mock_get_rooms, mock_request as mocked_federation_request:
+        with mock_get_rooms, mock_get_users, mock_request as mocked_federation_request:
             # Make the first query and sanity check it succeeds.
             response_1 = self.get_success(
                 e2e_handler.query_devices(
diff --git a/tests/handlers/test_federation_event.py b/tests/handlers/test_federation_event.py
index 51c8dd649822..918010cddbf9 100644
--- a/tests/handlers/test_federation_event.py
+++ b/tests/handlers/test_federation_event.py
@@ -11,14 +11,23 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from typing import Optional
 from unittest import mock
 
+from synapse.api.errors import AuthError
+from synapse.api.room_versions import RoomVersion
+from synapse.event_auth import (
+    check_state_dependent_auth_rules,
+    check_state_independent_auth_rules,
+)
 from synapse.events import make_event_from_dict
 from synapse.events.snapshot import EventContext
 from synapse.federation.transport.client import StateRequestResponse
 from synapse.logging.context import LoggingContext
 from synapse.rest import admin
 from synapse.rest.client import login, room
+from synapse.state.v2 import _mainline_sort, _reverse_topological_power_sort
+from synapse.types import JsonDict
 
 from tests import unittest
 from tests.test_utils import event_injection, make_awaitable
@@ -227,3 +236,615 @@ async def get_event(destination: str, event_id: str, timeout=None):
 
         if prev_exists_as_outlier:
             self.mock_federation_transport_client.get_event.assert_not_called()
+
+    def test_process_pulled_event_records_failed_backfill_attempts(
+        self,
+    ) -> None:
+        """
+        Test to make sure that failed backfill attempts for an event are
+        recorded in the `event_failed_pull_attempts` table.
+
+        In this test, we pretend we are processing a "pulled" event via
+        backfill. The pulled event has a fake `prev_event` which our server has
+        obviously never seen before so it attempts to request the state at that
+        `prev_event` which expectedly fails because it's a fake event. Because
+        the server can't fetch the state at the missing `prev_event`, the
+        "pulled" event fails the history check and is fails to process.
+
+        We check that we correctly record the number of failed pull attempts
+        of the pulled event and as a sanity check, that the "pulled" event isn't
+        persisted.
+        """
+        OTHER_USER = f"@user:{self.OTHER_SERVER_NAME}"
+        main_store = self.hs.get_datastores().main
+
+        # Create the room
+        user_id = self.register_user("kermit", "test")
+        tok = self.login("kermit", "test")
+        room_id = self.helper.create_room_as(room_creator=user_id, tok=tok)
+        room_version = self.get_success(main_store.get_room_version(room_id))
+
+        # We expect an outbound request to /state_ids, so stub that out
+        self.mock_federation_transport_client.get_room_state_ids.return_value = make_awaitable(
+            {
+                # Mimic the other server not knowing about the state at all.
+                # We want to cause Synapse to throw an error (`Unable to get
+                # missing prev_event $fake_prev_event`) and fail to backfill
+                # the pulled event.
+                "pdu_ids": [],
+                "auth_chain_ids": [],
+            }
+        )
+        # We also expect an outbound request to /state
+        self.mock_federation_transport_client.get_room_state.return_value = make_awaitable(
+            StateRequestResponse(
+                # Mimic the other server not knowing about the state at all.
+                # We want to cause Synapse to throw an error (`Unable to get
+                # missing prev_event $fake_prev_event`) and fail to backfill
+                # the pulled event.
+                auth_events=[],
+                state=[],
+            )
+        )
+
+        pulled_event = make_event_from_dict(
+            self.add_hashes_and_signatures_from_other_server(
+                {
+                    "type": "test_regular_type",
+                    "room_id": room_id,
+                    "sender": OTHER_USER,
+                    "prev_events": [
+                        # The fake prev event will make the pulled event fail
+                        # the history check (`Unable to get missing prev_event
+                        # $fake_prev_event`)
+                        "$fake_prev_event"
+                    ],
+                    "auth_events": [],
+                    "origin_server_ts": 1,
+                    "depth": 12,
+                    "content": {"body": "pulled"},
+                }
+            ),
+            room_version,
+        )
+
+        # The function under test: try to process the pulled event
+        with LoggingContext("test"):
+            self.get_success(
+                self.hs.get_federation_event_handler()._process_pulled_event(
+                    self.OTHER_SERVER_NAME, pulled_event, backfilled=True
+                )
+            )
+
+        # Make sure our failed pull attempt was recorded
+        backfill_num_attempts = self.get_success(
+            main_store.db_pool.simple_select_one_onecol(
+                table="event_failed_pull_attempts",
+                keyvalues={"event_id": pulled_event.event_id},
+                retcol="num_attempts",
+            )
+        )
+        self.assertEqual(backfill_num_attempts, 1)
+
+        # The function under test: try to process the pulled event again
+        with LoggingContext("test"):
+            self.get_success(
+                self.hs.get_federation_event_handler()._process_pulled_event(
+                    self.OTHER_SERVER_NAME, pulled_event, backfilled=True
+                )
+            )
+
+        # Make sure our second failed pull attempt was recorded (`num_attempts` was incremented)
+        backfill_num_attempts = self.get_success(
+            main_store.db_pool.simple_select_one_onecol(
+                table="event_failed_pull_attempts",
+                keyvalues={"event_id": pulled_event.event_id},
+                retcol="num_attempts",
+            )
+        )
+        self.assertEqual(backfill_num_attempts, 2)
+
+        # And as a sanity check, make sure the event was not persisted through all of this.
+        persisted = self.get_success(
+            main_store.get_event(pulled_event.event_id, allow_none=True)
+        )
+        self.assertIsNone(
+            persisted,
+            "pulled event that fails the history check should not be persisted at all",
+        )
+
+    def test_process_pulled_event_clears_backfill_attempts_after_being_successfully_persisted(
+        self,
+    ) -> None:
+        """
+        Test to make sure that failed pull attempts
+        (`event_failed_pull_attempts` table) for an event are cleared after the
+        event is successfully persisted.
+
+        In this test, we pretend we are processing a "pulled" event via
+        backfill. The pulled event succesfully processes and the backward
+        extremeties are updated along with clearing out any failed pull attempts
+        for those old extremities.
+
+        We check that we correctly cleared failed pull attempts of the
+        pulled event.
+        """
+        OTHER_USER = f"@user:{self.OTHER_SERVER_NAME}"
+        main_store = self.hs.get_datastores().main
+
+        # Create the room
+        user_id = self.register_user("kermit", "test")
+        tok = self.login("kermit", "test")
+        room_id = self.helper.create_room_as(room_creator=user_id, tok=tok)
+        room_version = self.get_success(main_store.get_room_version(room_id))
+
+        # allow the remote user to send state events
+        self.helper.send_state(
+            room_id,
+            "m.room.power_levels",
+            {"events_default": 0, "state_default": 0},
+            tok=tok,
+        )
+
+        # add the remote user to the room
+        member_event = self.get_success(
+            event_injection.inject_member_event(self.hs, room_id, OTHER_USER, "join")
+        )
+
+        initial_state_map = self.get_success(
+            main_store.get_partial_current_state_ids(room_id)
+        )
+
+        auth_event_ids = [
+            initial_state_map[("m.room.create", "")],
+            initial_state_map[("m.room.power_levels", "")],
+            member_event.event_id,
+        ]
+
+        pulled_event = make_event_from_dict(
+            self.add_hashes_and_signatures_from_other_server(
+                {
+                    "type": "test_regular_type",
+                    "room_id": room_id,
+                    "sender": OTHER_USER,
+                    "prev_events": [member_event.event_id],
+                    "auth_events": auth_event_ids,
+                    "origin_server_ts": 1,
+                    "depth": 12,
+                    "content": {"body": "pulled"},
+                }
+            ),
+            room_version,
+        )
+
+        # Fake the "pulled" event failing to backfill once so we can test
+        # if it's cleared out later on.
+        self.get_success(
+            main_store.record_event_failed_pull_attempt(
+                pulled_event.room_id, pulled_event.event_id, "fake cause"
+            )
+        )
+        # Make sure we have a failed pull attempt recorded for the pulled event
+        backfill_num_attempts = self.get_success(
+            main_store.db_pool.simple_select_one_onecol(
+                table="event_failed_pull_attempts",
+                keyvalues={"event_id": pulled_event.event_id},
+                retcol="num_attempts",
+            )
+        )
+        self.assertEqual(backfill_num_attempts, 1)
+
+        # The function under test: try to process the pulled event
+        with LoggingContext("test"):
+            self.get_success(
+                self.hs.get_federation_event_handler()._process_pulled_event(
+                    self.OTHER_SERVER_NAME, pulled_event, backfilled=True
+                )
+            )
+
+        # Make sure the failed pull attempts for the pulled event are cleared
+        backfill_num_attempts = self.get_success(
+            main_store.db_pool.simple_select_one_onecol(
+                table="event_failed_pull_attempts",
+                keyvalues={"event_id": pulled_event.event_id},
+                retcol="num_attempts",
+                allow_none=True,
+            )
+        )
+        self.assertIsNone(backfill_num_attempts)
+
+        # And as a sanity check, make sure the "pulled" event was persisted.
+        persisted = self.get_success(
+            main_store.get_event(pulled_event.event_id, allow_none=True)
+        )
+        self.assertIsNotNone(persisted, "pulled event was not persisted at all")
+
+    def test_process_pulled_event_with_rejected_missing_state(self) -> None:
+        """Ensure that we correctly handle pulled events with missing state containing a
+        rejected state event
+
+        In this test, we pretend we are processing a "pulled" event (eg, via backfill
+        or get_missing_events). The pulled event has a prev_event we haven't previously
+        seen, so the server requests the state at that prev_event. We expect the server
+        to make a /state request.
+
+        We simulate a remote server whose /state includes a rejected kick event for a
+        local user. Notably, the kick event is rejected only because it cites a rejected
+        auth event and would otherwise be accepted based on the room state. During state
+        resolution, we re-run auth and can potentially introduce such rejected events
+        into the state if we are not careful.
+
+        We check that the pulled event is correctly persisted, and that the state
+        afterwards does not include the rejected kick.
+        """
+        # The DAG we are testing looks like:
+        #
+        #                 ...
+        #                  |
+        #                  v
+        #       remote admin user joins
+        #                |   |
+        #        +-------+   +-------+
+        #        |                   |
+        #        |          rejected power levels
+        #        |           from remote server
+        #        |                   |
+        #        |                   v
+        #        |       rejected kick of local user
+        #        v           from remote server
+        # new power levels           |
+        #        |                   v
+        #        |             missing event
+        #        |           from remote server
+        #        |                   |
+        #        +-------+   +-------+
+        #                |   |
+        #                v   v
+        #             pulled event
+        #          from remote server
+        #
+        # (arrows are in the opposite direction to prev_events.)
+
+        OTHER_USER = f"@user:{self.OTHER_SERVER_NAME}"
+        main_store = self.hs.get_datastores().main
+
+        # Create the room.
+        kermit_user_id = self.register_user("kermit", "test")
+        kermit_tok = self.login("kermit", "test")
+        room_id = self.helper.create_room_as(
+            room_creator=kermit_user_id, tok=kermit_tok
+        )
+        room_version = self.get_success(main_store.get_room_version(room_id))
+
+        # Add another local user to the room. This user is going to be kicked in a
+        # rejected event.
+        bert_user_id = self.register_user("bert", "test")
+        bert_tok = self.login("bert", "test")
+        self.helper.join(room_id, user=bert_user_id, tok=bert_tok)
+
+        # Allow the remote user to kick bert.
+        # The remote user is going to send a rejected power levels event later on and we
+        # need state resolution to order it before another power levels event kermit is
+        # going to send later on. Hence we give both users the same power level, so that
+        # ties are broken by `origin_server_ts`.
+        self.helper.send_state(
+            room_id,
+            "m.room.power_levels",
+            {"users": {kermit_user_id: 100, OTHER_USER: 100}},
+            tok=kermit_tok,
+        )
+
+        # Add the remote user to the room.
+        other_member_event = self.get_success(
+            event_injection.inject_member_event(self.hs, room_id, OTHER_USER, "join")
+        )
+
+        initial_state_map = self.get_success(
+            main_store.get_partial_current_state_ids(room_id)
+        )
+        create_event = self.get_success(
+            main_store.get_event(initial_state_map[("m.room.create", "")])
+        )
+        bert_member_event = self.get_success(
+            main_store.get_event(initial_state_map[("m.room.member", bert_user_id)])
+        )
+        power_levels_event = self.get_success(
+            main_store.get_event(initial_state_map[("m.room.power_levels", "")])
+        )
+
+        # We now need a rejected state event that will fail
+        # `check_state_independent_auth_rules` but pass
+        # `check_state_dependent_auth_rules`.
+
+        # First, we create a power levels event that we pretend the remote server has
+        # accepted, but the local homeserver will reject.
+        next_depth = 100
+        next_timestamp = other_member_event.origin_server_ts + 100
+        rejected_power_levels_event = make_event_from_dict(
+            self.add_hashes_and_signatures_from_other_server(
+                {
+                    "type": "m.room.power_levels",
+                    "state_key": "",
+                    "room_id": room_id,
+                    "sender": OTHER_USER,
+                    "prev_events": [other_member_event.event_id],
+                    "auth_events": [
+                        initial_state_map[("m.room.create", "")],
+                        initial_state_map[("m.room.power_levels", "")],
+                        # The event will be rejected because of the duplicated auth
+                        # event.
+                        other_member_event.event_id,
+                        other_member_event.event_id,
+                    ],
+                    "origin_server_ts": next_timestamp,
+                    "depth": next_depth,
+                    "content": power_levels_event.content,
+                }
+            ),
+            room_version,
+        )
+        next_depth += 1
+        next_timestamp += 100
+
+        with LoggingContext("send_rejected_power_levels_event"):
+            self.get_success(
+                self.hs.get_federation_event_handler()._process_pulled_event(
+                    self.OTHER_SERVER_NAME,
+                    rejected_power_levels_event,
+                    backfilled=False,
+                )
+            )
+            self.assertEqual(
+                self.get_success(
+                    main_store.get_rejection_reason(
+                        rejected_power_levels_event.event_id
+                    )
+                ),
+                "auth_error",
+            )
+
+        # Then we create a kick event for a local user that cites the rejected power
+        # levels event in its auth events. The kick event will be rejected solely
+        # because of the rejected auth event and would otherwise be accepted.
+        rejected_kick_event = make_event_from_dict(
+            self.add_hashes_and_signatures_from_other_server(
+                {
+                    "type": "m.room.member",
+                    "state_key": bert_user_id,
+                    "room_id": room_id,
+                    "sender": OTHER_USER,
+                    "prev_events": [rejected_power_levels_event.event_id],
+                    "auth_events": [
+                        initial_state_map[("m.room.create", "")],
+                        rejected_power_levels_event.event_id,
+                        initial_state_map[("m.room.member", bert_user_id)],
+                        initial_state_map[("m.room.member", OTHER_USER)],
+                    ],
+                    "origin_server_ts": next_timestamp,
+                    "depth": next_depth,
+                    "content": {"membership": "leave"},
+                }
+            ),
+            room_version,
+        )
+        next_depth += 1
+        next_timestamp += 100
+
+        # The kick event must fail the state-independent auth rules, but pass the
+        # state-dependent auth rules, so that it has a chance of making it through state
+        # resolution.
+        self.get_failure(
+            check_state_independent_auth_rules(main_store, rejected_kick_event),
+            AuthError,
+        )
+        check_state_dependent_auth_rules(
+            rejected_kick_event,
+            [create_event, power_levels_event, other_member_event, bert_member_event],
+        )
+
+        # The kick event must also win over the original member event during state
+        # resolution.
+        self.assertEqual(
+            self.get_success(
+                _mainline_sort(
+                    self.clock,
+                    room_id,
+                    event_ids=[
+                        bert_member_event.event_id,
+                        rejected_kick_event.event_id,
+                    ],
+                    resolved_power_event_id=power_levels_event.event_id,
+                    event_map={
+                        bert_member_event.event_id: bert_member_event,
+                        rejected_kick_event.event_id: rejected_kick_event,
+                    },
+                    state_res_store=main_store,
+                )
+            ),
+            [bert_member_event.event_id, rejected_kick_event.event_id],
+            "The rejected kick event will not be applied after bert's join event "
+            "during state resolution. The test setup is incorrect.",
+        )
+
+        with LoggingContext("send_rejected_kick_event"):
+            self.get_success(
+                self.hs.get_federation_event_handler()._process_pulled_event(
+                    self.OTHER_SERVER_NAME, rejected_kick_event, backfilled=False
+                )
+            )
+            self.assertEqual(
+                self.get_success(
+                    main_store.get_rejection_reason(rejected_kick_event.event_id)
+                ),
+                "auth_error",
+            )
+
+        # We need another power levels event which will win over the rejected one during
+        # state resolution, otherwise we hit other issues where we end up with rejected
+        # a power levels event during state resolution.
+        self.reactor.advance(100)  # ensure the `origin_server_ts` is larger
+        new_power_levels_event = self.get_success(
+            main_store.get_event(
+                self.helper.send_state(
+                    room_id,
+                    "m.room.power_levels",
+                    {"users": {kermit_user_id: 100, OTHER_USER: 100, bert_user_id: 1}},
+                    tok=kermit_tok,
+                )["event_id"]
+            )
+        )
+        self.assertEqual(
+            self.get_success(
+                _reverse_topological_power_sort(
+                    self.clock,
+                    room_id,
+                    event_ids=[
+                        new_power_levels_event.event_id,
+                        rejected_power_levels_event.event_id,
+                    ],
+                    event_map={},
+                    state_res_store=main_store,
+                    full_conflicted_set=set(),
+                )
+            ),
+            [rejected_power_levels_event.event_id, new_power_levels_event.event_id],
+            "The power levels events will not have the desired ordering during state "
+            "resolution. The test setup is incorrect.",
+        )
+
+        # Create a missing event, so that the local homeserver has to do a `/state` or
+        # `/state_ids` request to pull state from the remote homeserver.
+        missing_event = make_event_from_dict(
+            self.add_hashes_and_signatures_from_other_server(
+                {
+                    "type": "m.room.message",
+                    "room_id": room_id,
+                    "sender": OTHER_USER,
+                    "prev_events": [rejected_kick_event.event_id],
+                    "auth_events": [
+                        initial_state_map[("m.room.create", "")],
+                        initial_state_map[("m.room.power_levels", "")],
+                        initial_state_map[("m.room.member", OTHER_USER)],
+                    ],
+                    "origin_server_ts": next_timestamp,
+                    "depth": next_depth,
+                    "content": {"msgtype": "m.text", "body": "foo"},
+                }
+            ),
+            room_version,
+        )
+        next_depth += 1
+        next_timestamp += 100
+
+        # The pulled event has two prev events, one of which is missing. We will make a
+        # `/state` or `/state_ids` request to the remote homeserver to ask it for the
+        # state before the missing prev event.
+        pulled_event = make_event_from_dict(
+            self.add_hashes_and_signatures_from_other_server(
+                {
+                    "type": "m.room.message",
+                    "room_id": room_id,
+                    "sender": OTHER_USER,
+                    "prev_events": [
+                        new_power_levels_event.event_id,
+                        missing_event.event_id,
+                    ],
+                    "auth_events": [
+                        initial_state_map[("m.room.create", "")],
+                        new_power_levels_event.event_id,
+                        initial_state_map[("m.room.member", OTHER_USER)],
+                    ],
+                    "origin_server_ts": next_timestamp,
+                    "depth": next_depth,
+                    "content": {"msgtype": "m.text", "body": "bar"},
+                }
+            ),
+            room_version,
+        )
+        next_depth += 1
+        next_timestamp += 100
+
+        # Prepare the response for the `/state` or `/state_ids` request.
+        # The remote server believes bert has been kicked, while the local server does
+        # not.
+        state_before_missing_event = self.get_success(
+            main_store.get_events_as_list(initial_state_map.values())
+        )
+        state_before_missing_event = [
+            event
+            for event in state_before_missing_event
+            if event.event_id != bert_member_event.event_id
+        ]
+        state_before_missing_event.append(rejected_kick_event)
+
+        # We have to bump the clock a bit, to keep the retry logic in
+        # `FederationClient.get_pdu` happy
+        self.reactor.advance(60000)
+        with LoggingContext("send_pulled_event"):
+
+            async def get_event(
+                destination: str, event_id: str, timeout: Optional[int] = None
+            ) -> JsonDict:
+                self.assertEqual(destination, self.OTHER_SERVER_NAME)
+                self.assertEqual(event_id, missing_event.event_id)
+                return {"pdus": [missing_event.get_pdu_json()]}
+
+            async def get_room_state_ids(
+                destination: str, room_id: str, event_id: str
+            ) -> JsonDict:
+                self.assertEqual(destination, self.OTHER_SERVER_NAME)
+                self.assertEqual(event_id, missing_event.event_id)
+                return {
+                    "pdu_ids": [event.event_id for event in state_before_missing_event],
+                    "auth_chain_ids": [],
+                }
+
+            async def get_room_state(
+                room_version: RoomVersion, destination: str, room_id: str, event_id: str
+            ) -> StateRequestResponse:
+                self.assertEqual(destination, self.OTHER_SERVER_NAME)
+                self.assertEqual(event_id, missing_event.event_id)
+                return StateRequestResponse(
+                    state=state_before_missing_event,
+                    auth_events=[],
+                )
+
+            self.mock_federation_transport_client.get_event.side_effect = get_event
+            self.mock_federation_transport_client.get_room_state_ids.side_effect = (
+                get_room_state_ids
+            )
+            self.mock_federation_transport_client.get_room_state.side_effect = (
+                get_room_state
+            )
+
+            self.get_success(
+                self.hs.get_federation_event_handler()._process_pulled_event(
+                    self.OTHER_SERVER_NAME, pulled_event, backfilled=False
+                )
+            )
+            self.assertIsNone(
+                self.get_success(
+                    main_store.get_rejection_reason(pulled_event.event_id)
+                ),
+                "Pulled event was unexpectedly rejected, likely due to a problem with "
+                "the test setup.",
+            )
+            self.assertEqual(
+                {pulled_event.event_id},
+                self.get_success(
+                    main_store.have_events_in_timeline([pulled_event.event_id])
+                ),
+                "Pulled event was not persisted, likely due to a problem with the test "
+                "setup.",
+            )
+
+            # We must not accept rejected events into the room state, so we expect bert
+            # to not be kicked, even if the remote server believes so.
+            new_state_map = self.get_success(
+                main_store.get_partial_current_state_ids(room_id)
+            )
+            self.assertEqual(
+                new_state_map[("m.room.member", bert_user_id)],
+                bert_member_event.event_id,
+                "Rejected kick event unexpectedly became part of room state.",
+            )
diff --git a/tests/http/server/_base.py b/tests/http/server/_base.py
index 5726e60cee7c..5071f835745e 100644
--- a/tests/http/server/_base.py
+++ b/tests/http/server/_base.py
@@ -140,6 +140,8 @@ def make_request_with_cancellation_test(
     method: str,
     path: str,
     content: Union[bytes, str, JsonDict] = b"",
+    *,
+    token: Optional[str] = None,
 ) -> FakeChannel:
     """Performs a request repeatedly, disconnecting at successive `await`s, until
     one completes.
@@ -211,7 +213,13 @@ def make_request_with_cancellation_test(
                 with deferred_patch.patch():
                     # Start the request.
                     channel = make_request(
-                        reactor, site, method, path, content, await_result=False
+                        reactor,
+                        site,
+                        method,
+                        path,
+                        content,
+                        await_result=False,
+                        access_token=token,
                     )
                     request = channel.request
 
diff --git a/tests/replication/slave/storage/test_events.py b/tests/replication/slave/storage/test_events.py
index 09bfc6ca6f8a..7497c15f915a 100644
--- a/tests/replication/slave/storage/test_events.py
+++ b/tests/replication/slave/storage/test_events.py
@@ -404,6 +404,7 @@ def build_event(
                 event.event_id,
                 {user_id: actions for user_id, actions in push_actions},
                 {user_id: False for user_id, _ in push_actions},
+                "main",
             )
         )
         return event, context
diff --git a/tests/rest/admin/test_room.py b/tests/rest/admin/test_room.py
index 9d71a9752449..d156be82b04d 100644
--- a/tests/rest/admin/test_room.py
+++ b/tests/rest/admin/test_room.py
@@ -11,6 +11,8 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import json
+import time
 import urllib.parse
 from typing import List, Optional
 from unittest.mock import Mock
@@ -22,10 +24,11 @@
 import synapse.rest.admin
 from synapse.api.constants import EventTypes, Membership, RoomTypes
 from synapse.api.errors import Codes
-from synapse.handlers.pagination import PaginationHandler
+from synapse.handlers.pagination import PaginationHandler, PurgeStatus
 from synapse.rest.client import directory, events, login, room
 from synapse.server import HomeServer
 from synapse.util import Clock
+from synapse.util.stringutils import random_string
 
 from tests import unittest
 
@@ -1793,6 +1796,159 @@ def test_get_joined_members_after_leave_room(self) -> None:
         self.assertEqual(Codes.FORBIDDEN, channel.json_body["errcode"])
 
 
+class RoomMessagesTestCase(unittest.HomeserverTestCase):
+    servlets = [
+        synapse.rest.admin.register_servlets,
+        login.register_servlets,
+        room.register_servlets,
+    ]
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.admin_user = self.register_user("admin", "pass", admin=True)
+        self.admin_user_tok = self.login("admin", "pass")
+
+        self.user = self.register_user("foo", "pass")
+        self.user_tok = self.login("foo", "pass")
+        self.room_id = self.helper.create_room_as(self.user, tok=self.user_tok)
+
+    def test_timestamp_to_event(self) -> None:
+        """Test that providing the current timestamp can get the last event."""
+        self.helper.send(self.room_id, body="message 1", tok=self.user_tok)
+        second_event_id = self.helper.send(
+            self.room_id, body="message 2", tok=self.user_tok
+        )["event_id"]
+        ts = str(round(time.time() * 1000))
+
+        channel = self.make_request(
+            "GET",
+            "/_synapse/admin/v1/rooms/%s/timestamp_to_event?dir=b&ts=%s"
+            % (self.room_id, ts),
+            access_token=self.admin_user_tok,
+        )
+        self.assertEqual(200, channel.code)
+        self.assertIn("event_id", channel.json_body)
+        self.assertEqual(second_event_id, channel.json_body["event_id"])
+
+    def test_topo_token_is_accepted(self) -> None:
+        """Test Topo Token is accepted."""
+        token = "t1-0_0_0_0_0_0_0_0_0"
+        channel = self.make_request(
+            "GET",
+            "/_synapse/admin/v1/rooms/%s/messages?from=%s" % (self.room_id, token),
+            access_token=self.admin_user_tok,
+        )
+        self.assertEqual(200, channel.code)
+        self.assertIn("start", channel.json_body)
+        self.assertEqual(token, channel.json_body["start"])
+        self.assertIn("chunk", channel.json_body)
+        self.assertIn("end", channel.json_body)
+
+    def test_stream_token_is_accepted_for_fwd_pagianation(self) -> None:
+        """Test that stream token is accepted for forward pagination."""
+        token = "s0_0_0_0_0_0_0_0_0"
+        channel = self.make_request(
+            "GET",
+            "/_synapse/admin/v1/rooms/%s/messages?from=%s" % (self.room_id, token),
+            access_token=self.admin_user_tok,
+        )
+        self.assertEqual(200, channel.code)
+        self.assertIn("start", channel.json_body)
+        self.assertEqual(token, channel.json_body["start"])
+        self.assertIn("chunk", channel.json_body)
+        self.assertIn("end", channel.json_body)
+
+    def test_room_messages_purge(self) -> None:
+        """Test room messages can be retrieved by an admin that isn't in the room."""
+        store = self.hs.get_datastores().main
+        pagination_handler = self.hs.get_pagination_handler()
+
+        # Send a first message in the room, which will be removed by the purge.
+        first_event_id = self.helper.send(
+            self.room_id, body="message 1", tok=self.user_tok
+        )["event_id"]
+        first_token = self.get_success(
+            store.get_topological_token_for_event(first_event_id)
+        )
+        first_token_str = self.get_success(first_token.to_string(store))
+
+        # Send a second message in the room, which won't be removed, and which we'll
+        # use as the marker to purge events before.
+        second_event_id = self.helper.send(
+            self.room_id, body="message 2", tok=self.user_tok
+        )["event_id"]
+        second_token = self.get_success(
+            store.get_topological_token_for_event(second_event_id)
+        )
+        second_token_str = self.get_success(second_token.to_string(store))
+
+        # Send a third event in the room to ensure we don't fall under any edge case
+        # due to our marker being the latest forward extremity in the room.
+        self.helper.send(self.room_id, body="message 3", tok=self.user_tok)
+
+        # Check that we get the first and second message when querying /messages.
+        channel = self.make_request(
+            "GET",
+            "/_synapse/admin/v1/rooms/%s/messages?from=%s&dir=b&filter=%s"
+            % (
+                self.room_id,
+                second_token_str,
+                json.dumps({"types": [EventTypes.Message]}),
+            ),
+            access_token=self.admin_user_tok,
+        )
+        self.assertEqual(channel.code, 200, channel.json_body)
+
+        chunk = channel.json_body["chunk"]
+        self.assertEqual(len(chunk), 2, [event["content"] for event in chunk])
+
+        # Purge every event before the second event.
+        purge_id = random_string(16)
+        pagination_handler._purges_by_id[purge_id] = PurgeStatus()
+        self.get_success(
+            pagination_handler._purge_history(
+                purge_id=purge_id,
+                room_id=self.room_id,
+                token=second_token_str,
+                delete_local_events=True,
+            )
+        )
+
+        # Check that we only get the second message through /message now that the first
+        # has been purged.
+        channel = self.make_request(
+            "GET",
+            "/_synapse/admin/v1/rooms/%s/messages?from=%s&dir=b&filter=%s"
+            % (
+                self.room_id,
+                second_token_str,
+                json.dumps({"types": [EventTypes.Message]}),
+            ),
+            access_token=self.admin_user_tok,
+        )
+        self.assertEqual(channel.code, 200, channel.json_body)
+
+        chunk = channel.json_body["chunk"]
+        self.assertEqual(len(chunk), 1, [event["content"] for event in chunk])
+
+        # Check that we get no event, but also no error, when querying /messages with
+        # the token that was pointing at the first event, because we don't have it
+        # anymore.
+        channel = self.make_request(
+            "GET",
+            "/_synapse/admin/v1/rooms/%s/messages?from=%s&dir=b&filter=%s"
+            % (
+                self.room_id,
+                first_token_str,
+                json.dumps({"types": [EventTypes.Message]}),
+            ),
+            access_token=self.admin_user_tok,
+        )
+        self.assertEqual(channel.code, 200, channel.json_body)
+
+        chunk = channel.json_body["chunk"]
+        self.assertEqual(len(chunk), 0, [event["content"] for event in chunk])
+
+
 class JoinAliasRoomTestCase(unittest.HomeserverTestCase):
 
     servlets = [
diff --git a/tests/rest/admin/test_user.py b/tests/rest/admin/test_user.py
index 1afd082707c2..9f536ceeb345 100644
--- a/tests/rest/admin/test_user.py
+++ b/tests/rest/admin/test_user.py
@@ -2580,6 +2580,7 @@ def _check_fields(self, content: JsonDict) -> None:
         self.assertIn("appservice_id", content)
         self.assertIn("consent_server_notice_sent", content)
         self.assertIn("consent_version", content)
+        self.assertIn("consent_ts", content)
         self.assertIn("external_ids", content)
 
         # This key was removed intentionally. Ensure it is not accidentally re-included.
@@ -4139,3 +4140,90 @@ def test_success(self) -> None:
             {"b": 2},
             channel.json_body["account_data"]["rooms"]["test_room"]["m.per_room"],
         )
+
+
+class UsersByExternalIdTestCase(unittest.HomeserverTestCase):
+
+    servlets = [
+        synapse.rest.admin.register_servlets,
+        login.register_servlets,
+    ]
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.store = hs.get_datastores().main
+
+        self.admin_user = self.register_user("admin", "pass", admin=True)
+        self.admin_user_tok = self.login("admin", "pass")
+
+        self.other_user = self.register_user("user", "pass")
+        self.get_success(
+            self.store.record_user_external_id(
+                "the-auth-provider", "the-external-id", self.other_user
+            )
+        )
+        self.get_success(
+            self.store.record_user_external_id(
+                "another-auth-provider", "a:complex@external/id", self.other_user
+            )
+        )
+
+    def test_no_auth(self) -> None:
+        """Try to lookup a user without authentication."""
+        url = (
+            "/_synapse/admin/v1/auth_providers/the-auth-provider/users/the-external-id"
+        )
+
+        channel = self.make_request(
+            "GET",
+            url,
+        )
+
+        self.assertEqual(401, channel.code, msg=channel.json_body)
+        self.assertEqual(Codes.MISSING_TOKEN, channel.json_body["errcode"])
+
+    def test_binding_does_not_exist(self) -> None:
+        """Tests that a lookup for an external ID that does not exist returns a 404"""
+        url = "/_synapse/admin/v1/auth_providers/the-auth-provider/users/unknown-id"
+
+        channel = self.make_request(
+            "GET",
+            url,
+            access_token=self.admin_user_tok,
+        )
+
+        self.assertEqual(404, channel.code, msg=channel.json_body)
+        self.assertEqual(Codes.NOT_FOUND, channel.json_body["errcode"])
+
+    def test_success(self) -> None:
+        """Tests a successful external ID lookup"""
+        url = (
+            "/_synapse/admin/v1/auth_providers/the-auth-provider/users/the-external-id"
+        )
+
+        channel = self.make_request(
+            "GET",
+            url,
+            access_token=self.admin_user_tok,
+        )
+
+        self.assertEqual(200, channel.code, msg=channel.json_body)
+        self.assertEqual(
+            {"user_id": self.other_user},
+            channel.json_body,
+        )
+
+    def test_success_urlencoded(self) -> None:
+        """Tests a successful external ID lookup with an url-encoded ID"""
+        url = "/_synapse/admin/v1/auth_providers/another-auth-provider/users/a%3Acomplex%40external%2Fid"
+
+        channel = self.make_request(
+            "GET",
+            url,
+            access_token=self.admin_user_tok,
+        )
+
+        self.assertEqual(200, channel.code, msg=channel.json_body)
+        self.assertEqual(
+            {"user_id": self.other_user},
+            channel.json_body,
+        )
diff --git a/tests/rest/client/test_keys.py b/tests/rest/client/test_keys.py
index bbc8e7424351..741fecea7713 100644
--- a/tests/rest/client/test_keys.py
+++ b/tests/rest/client/test_keys.py
@@ -19,6 +19,7 @@
 from synapse.rest.client import keys, login
 
 from tests import unittest
+from tests.http.server._base import make_request_with_cancellation_test
 
 
 class KeyQueryTestCase(unittest.HomeserverTestCase):
@@ -89,3 +90,31 @@ def test_requires_device_key(self) -> None:
             Codes.BAD_JSON,
             channel.result,
         )
+
+    def test_key_query_cancellation(self) -> None:
+        """
+        Tests that /keys/query is cancellable and does not swallow the
+        CancelledError.
+        """
+        self.register_user("alice", "wonderland")
+        alice_token = self.login("alice", "wonderland")
+
+        bob = self.register_user("bob", "uncle")
+
+        channel = make_request_with_cancellation_test(
+            "test_key_query_cancellation",
+            self.reactor,
+            self.site,
+            "POST",
+            "/_matrix/client/r0/keys/query",
+            {
+                "device_keys": {
+                    # Empty list means we request keys for all bob's devices
+                    bob: [],
+                },
+            },
+            token=alice_token,
+        )
+
+        self.assertEqual(200, channel.code, msg=channel.result["body"])
+        self.assertIn(bob, channel.json_body["device_keys"])
diff --git a/tests/rest/client/test_models.py b/tests/rest/client/test_models.py
index a9da00665e19..0b8fcb0c47f4 100644
--- a/tests/rest/client/test_models.py
+++ b/tests/rest/client/test_models.py
@@ -11,14 +11,37 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import unittest
+import unittest as stdlib_unittest
 
-from pydantic import ValidationError
+from pydantic import BaseModel, ValidationError
+from typing_extensions import Literal
 
 from synapse.rest.client.models import EmailRequestTokenBody
 
 
-class EmailRequestTokenBodyTestCase(unittest.TestCase):
+class ThreepidMediumEnumTestCase(stdlib_unittest.TestCase):
+    class Model(BaseModel):
+        medium: Literal["email", "msisdn"]
+
+    def test_accepts_valid_medium_string(self) -> None:
+        """Sanity check that Pydantic behaves sensibly with an enum-of-str
+
+        This is arguably more of a test of a class that inherits from str and Enum
+        simultaneously.
+        """
+        model = self.Model.parse_obj({"medium": "email"})
+        self.assertEqual(model.medium, "email")
+
+    def test_rejects_invalid_medium_value(self) -> None:
+        with self.assertRaises(ValidationError):
+            self.Model.parse_obj({"medium": "interpretive_dance"})
+
+    def test_rejects_invalid_medium_type(self) -> None:
+        with self.assertRaises(ValidationError):
+            self.Model.parse_obj({"medium": 123})
+
+
+class EmailRequestTokenBodyTestCase(stdlib_unittest.TestCase):
     base_request = {
         "client_secret": "hunter2",
         "email": "alice@wonderland.com",
diff --git a/tests/rest/media/test_media_retention.py b/tests/rest/media/test_media_retention.py
index 14af07c5af96..23f227aed69f 100644
--- a/tests/rest/media/test_media_retention.py
+++ b/tests/rest/media/test_media_retention.py
@@ -13,7 +13,9 @@
 # limitations under the License.
 
 import io
-from typing import Iterable, Optional, Tuple
+from typing import Iterable, Optional
+
+from matrix_common.types.mxc_uri import MXCUri
 
 from twisted.test.proto_helpers import MemoryReactor
 
@@ -63,9 +65,9 @@ def _create_media_and_set_attributes(
             last_accessed_ms: Optional[int],
             is_quarantined: Optional[bool] = False,
             is_protected: Optional[bool] = False,
-        ) -> str:
+        ) -> MXCUri:
             # "Upload" some media to the local media store
-            mxc_uri = self.get_success(
+            mxc_uri: MXCUri = self.get_success(
                 media_repository.create_content(
                     media_type="text/plain",
                     upload_name=None,
@@ -75,13 +77,11 @@ def _create_media_and_set_attributes(
                 )
             )
 
-            media_id = mxc_uri.split("/")[-1]
-
             # Set the last recently accessed time for this media
             if last_accessed_ms is not None:
                 self.get_success(
                     self.store.update_cached_last_access_time(
-                        local_media=(media_id,),
+                        local_media=(mxc_uri.media_id,),
                         remote_media=(),
                         time_ms=last_accessed_ms,
                     )
@@ -92,7 +92,7 @@ def _create_media_and_set_attributes(
                 self.get_success(
                     self.store.quarantine_media_by_id(
                         server_name=self.hs.config.server.server_name,
-                        media_id=media_id,
+                        media_id=mxc_uri.media_id,
                         quarantined_by="@theadmin:test",
                     )
                 )
@@ -101,18 +101,18 @@ def _create_media_and_set_attributes(
                 # Mark this media as protected from quarantine
                 self.get_success(
                     self.store.mark_local_media_as_safe(
-                        media_id=media_id,
+                        media_id=mxc_uri.media_id,
                         safe=True,
                     )
                 )
 
-            return media_id
+            return mxc_uri
 
         def _cache_remote_media_and_set_attributes(
             media_id: str,
             last_accessed_ms: Optional[int],
             is_quarantined: Optional[bool] = False,
-        ) -> str:
+        ) -> MXCUri:
             # Pretend to cache some remote media
             self.get_success(
                 self.store.store_cached_remote_media(
@@ -146,7 +146,7 @@ def _cache_remote_media_and_set_attributes(
                     )
                 )
 
-            return media_id
+            return MXCUri(self.remote_server_name, media_id)
 
         # Start with the local media store
         self.local_recently_accessed_media = _create_media_and_set_attributes(
@@ -214,28 +214,16 @@ def test_local_media_retention(self) -> None:
         # Remote media should be unaffected.
         self._assert_if_mxc_uris_purged(
             purged=[
-                (
-                    self.hs.config.server.server_name,
-                    self.local_not_recently_accessed_media,
-                ),
-                (self.hs.config.server.server_name, self.local_never_accessed_media),
+                self.local_not_recently_accessed_media,
+                self.local_never_accessed_media,
             ],
             not_purged=[
-                (self.hs.config.server.server_name, self.local_recently_accessed_media),
-                (
-                    self.hs.config.server.server_name,
-                    self.local_not_recently_accessed_quarantined_media,
-                ),
-                (
-                    self.hs.config.server.server_name,
-                    self.local_not_recently_accessed_protected_media,
-                ),
-                (self.remote_server_name, self.remote_recently_accessed_media),
-                (self.remote_server_name, self.remote_not_recently_accessed_media),
-                (
-                    self.remote_server_name,
-                    self.remote_not_recently_accessed_quarantined_media,
-                ),
+                self.local_recently_accessed_media,
+                self.local_not_recently_accessed_quarantined_media,
+                self.local_not_recently_accessed_protected_media,
+                self.remote_recently_accessed_media,
+                self.remote_not_recently_accessed_media,
+                self.remote_not_recently_accessed_quarantined_media,
             ],
         )
 
@@ -261,49 +249,35 @@ def test_remote_media_cache_retention(self) -> None:
         # Remote media accessed <30 days ago should still exist.
         self._assert_if_mxc_uris_purged(
             purged=[
-                (self.remote_server_name, self.remote_not_recently_accessed_media),
+                self.remote_not_recently_accessed_media,
             ],
             not_purged=[
-                (self.remote_server_name, self.remote_recently_accessed_media),
-                (self.hs.config.server.server_name, self.local_recently_accessed_media),
-                (
-                    self.hs.config.server.server_name,
-                    self.local_not_recently_accessed_media,
-                ),
-                (
-                    self.hs.config.server.server_name,
-                    self.local_not_recently_accessed_quarantined_media,
-                ),
-                (
-                    self.hs.config.server.server_name,
-                    self.local_not_recently_accessed_protected_media,
-                ),
-                (
-                    self.remote_server_name,
-                    self.remote_not_recently_accessed_quarantined_media,
-                ),
-                (self.hs.config.server.server_name, self.local_never_accessed_media),
+                self.remote_recently_accessed_media,
+                self.local_recently_accessed_media,
+                self.local_not_recently_accessed_media,
+                self.local_not_recently_accessed_quarantined_media,
+                self.local_not_recently_accessed_protected_media,
+                self.remote_not_recently_accessed_quarantined_media,
+                self.local_never_accessed_media,
             ],
         )
 
     def _assert_if_mxc_uris_purged(
-        self, purged: Iterable[Tuple[str, str]], not_purged: Iterable[Tuple[str, str]]
+        self, purged: Iterable[MXCUri], not_purged: Iterable[MXCUri]
     ) -> None:
-        def _assert_mxc_uri_purge_state(
-            server_name: str, media_id: str, expect_purged: bool
-        ) -> None:
+        def _assert_mxc_uri_purge_state(mxc_uri: MXCUri, expect_purged: bool) -> None:
             """Given an MXC URI, assert whether it has been purged or not."""
-            if server_name == self.hs.config.server.server_name:
+            if mxc_uri.server_name == self.hs.config.server.server_name:
                 found_media_dict = self.get_success(
-                    self.store.get_local_media(media_id)
+                    self.store.get_local_media(mxc_uri.media_id)
                 )
             else:
                 found_media_dict = self.get_success(
-                    self.store.get_cached_remote_media(server_name, media_id)
+                    self.store.get_cached_remote_media(
+                        mxc_uri.server_name, mxc_uri.media_id
+                    )
                 )
 
-            mxc_uri = f"mxc://{server_name}/{media_id}"
-
             if expect_purged:
                 self.assertIsNone(
                     found_media_dict, msg=f"{mxc_uri} unexpectedly not purged"
@@ -315,7 +289,7 @@ def _assert_mxc_uri_purge_state(
                 )
 
         # Assert that the given MXC URIs have either been correctly purged or not.
-        for server_name, media_id in purged:
-            _assert_mxc_uri_purge_state(server_name, media_id, expect_purged=True)
-        for server_name, media_id in not_purged:
-            _assert_mxc_uri_purge_state(server_name, media_id, expect_purged=False)
+        for mxc_uri in purged:
+            _assert_mxc_uri_purge_state(mxc_uri, expect_purged=True)
+        for mxc_uri in not_purged:
+            _assert_mxc_uri_purge_state(mxc_uri, expect_purged=False)
diff --git a/tests/storage/databases/main/test_events_worker.py b/tests/storage/databases/main/test_events_worker.py
index 46d829b062a0..67401272ac37 100644
--- a/tests/storage/databases/main/test_events_worker.py
+++ b/tests/storage/databases/main/test_events_worker.py
@@ -254,7 +254,7 @@ def _populate_events(self) -> None:
                         "room_id": self.room_id,
                         "json": json.dumps(event_json),
                         "internal_metadata": "{}",
-                        "format_version": EventFormatVersions.V3,
+                        "format_version": EventFormatVersions.ROOM_V4_PLUS,
                     },
                 )
             )
diff --git a/tests/storage/test_base.py b/tests/storage/test_base.py
index cce8e75c7475..40e58f8199d0 100644
--- a/tests/storage/test_base.py
+++ b/tests/storage/test_base.py
@@ -54,7 +54,6 @@ def runWithConnection(func, *args, **kwargs):
         sqlite_config = {"name": "sqlite3"}
         engine = create_engine(sqlite_config)
         fake_engine = Mock(wraps=engine)
-        fake_engine.can_native_upsert = False
         fake_engine.in_transaction.return_value = False
 
         db = DatabasePool(Mock(), Mock(config=sqlite_config), fake_engine)
diff --git a/tests/storage/test_event_federation.py b/tests/storage/test_event_federation.py
index d92a9ac5b798..a6679e131201 100644
--- a/tests/storage/test_event_federation.py
+++ b/tests/storage/test_event_federation.py
@@ -513,7 +513,7 @@ def test_prune_inbound_federation_queue(self, room_version: RoomVersion):
 
         def prev_event_format(prev_event_id: str) -> Union[Tuple[str, dict], str]:
             """Account for differences in prev_events format across room versions"""
-            if room_version.event_format == EventFormatVersions.V1:
+            if room_version.event_format == EventFormatVersions.ROOM_V1_V2:
                 return prev_event_id, {}
 
             return prev_event_id
diff --git a/tests/storage/test_registration.py b/tests/storage/test_registration.py
index a49ac1525ec7..853a93afab39 100644
--- a/tests/storage/test_registration.py
+++ b/tests/storage/test_registration.py
@@ -11,15 +11,18 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from twisted.test.proto_helpers import MemoryReactor
 
 from synapse.api.constants import UserTypes
 from synapse.api.errors import ThreepidValidationError
+from synapse.server import HomeServer
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
 
 class RegistrationStoreTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
 
         self.user_id = "@my-user:test"
@@ -27,7 +30,7 @@ def prepare(self, reactor, clock, hs):
         self.pwhash = "{xx1}123456789"
         self.device_id = "akgjhdjklgshg"
 
-    def test_register(self):
+    def test_register(self) -> None:
         self.get_success(self.store.register_user(self.user_id, self.pwhash))
 
         self.assertEqual(
@@ -38,6 +41,7 @@ def test_register(self):
                 "admin": 0,
                 "is_guest": 0,
                 "consent_version": None,
+                "consent_ts": None,
                 "consent_server_notice_sent": None,
                 "appservice_id": None,
                 "creation_ts": 0,
@@ -48,7 +52,20 @@ def test_register(self):
             (self.get_success(self.store.get_user_by_id(self.user_id))),
         )
 
-    def test_add_tokens(self):
+    def test_consent(self) -> None:
+        self.get_success(self.store.register_user(self.user_id, self.pwhash))
+        before_consent = self.clock.time_msec()
+        self.reactor.advance(5)
+        self.get_success(self.store.user_set_consent_version(self.user_id, "1"))
+        self.reactor.advance(5)
+
+        user = self.get_success(self.store.get_user_by_id(self.user_id))
+        assert user
+        self.assertEqual(user["consent_version"], "1")
+        self.assertGreater(user["consent_ts"], before_consent)
+        self.assertLess(user["consent_ts"], self.clock.time_msec())
+
+    def test_add_tokens(self) -> None:
         self.get_success(self.store.register_user(self.user_id, self.pwhash))
         self.get_success(
             self.store.add_access_token_to_user(
@@ -58,11 +75,12 @@ def test_add_tokens(self):
 
         result = self.get_success(self.store.get_user_by_access_token(self.tokens[1]))
 
+        assert result
         self.assertEqual(result.user_id, self.user_id)
         self.assertEqual(result.device_id, self.device_id)
         self.assertIsNotNone(result.token_id)
 
-    def test_user_delete_access_tokens(self):
+    def test_user_delete_access_tokens(self) -> None:
         # add some tokens
         self.get_success(self.store.register_user(self.user_id, self.pwhash))
         self.get_success(
@@ -87,6 +105,7 @@ def test_user_delete_access_tokens(self):
 
         # check the one not associated with the device was not deleted
         user = self.get_success(self.store.get_user_by_access_token(self.tokens[0]))
+        assert user
         self.assertEqual(self.user_id, user.user_id)
 
         # now delete the rest
@@ -95,11 +114,11 @@ def test_user_delete_access_tokens(self):
         user = self.get_success(self.store.get_user_by_access_token(self.tokens[0]))
         self.assertIsNone(user, "access token was not deleted without device_id")
 
-    def test_is_support_user(self):
+    def test_is_support_user(self) -> None:
         TEST_USER = "@test:test"
         SUPPORT_USER = "@support:test"
 
-        res = self.get_success(self.store.is_support_user(None))
+        res = self.get_success(self.store.is_support_user(None))  # type: ignore[arg-type]
         self.assertFalse(res)
         self.get_success(
             self.store.register_user(user_id=TEST_USER, password_hash=None)
@@ -115,7 +134,7 @@ def test_is_support_user(self):
         res = self.get_success(self.store.is_support_user(SUPPORT_USER))
         self.assertTrue(res)
 
-    def test_3pid_inhibit_invalid_validation_session_error(self):
+    def test_3pid_inhibit_invalid_validation_session_error(self) -> None:
         """Tests that enabling the configuration option to inhibit 3PID errors on
         /requestToken also inhibits validation errors caused by an unknown session ID.
         """
diff --git a/tests/test_event_auth.py b/tests/test_event_auth.py
index e42d7b9ba080..f4d9fba0a14c 100644
--- a/tests/test_event_auth.py
+++ b/tests/test_event_auth.py
@@ -821,7 +821,7 @@ def _alias_event(room_version: RoomVersion, sender: str, **kwargs) -> EventBase:
 def _build_auth_dict_for_room_version(
     room_version: RoomVersion, auth_events: Iterable[EventBase]
 ) -> List:
-    if room_version.event_format == EventFormatVersions.V1:
+    if room_version.event_format == EventFormatVersions.ROOM_V1_V2:
         return [(e.event_id, "not_used") for e in auth_events]
     else:
         return [e.event_id for e in auth_events]
@@ -871,7 +871,7 @@ def _join_rules_event(
 
 def _maybe_get_event_id_dict_for_room_version(room_version: RoomVersion) -> dict:
     """If this room version needs it, generate an event id"""
-    if room_version.event_format != EventFormatVersions.V1:
+    if room_version.event_format != EventFormatVersions.ROOM_V1_V2:
         return {}
 
     global event_count
diff --git a/tests/test_rust.py b/tests/test_rust.py
new file mode 100644
index 000000000000..55d8b6b28cb4
--- /dev/null
+++ b/tests/test_rust.py
@@ -0,0 +1,11 @@
+from synapse.synapse_rust import sum_as_string
+
+from tests import unittest
+
+
+class RustTestCase(unittest.TestCase):
+    """Basic tests to ensure that we can call into Rust code."""
+
+    def test_basic(self):
+        result = sum_as_string(1, 2)
+        self.assertEqual("3", result)
diff --git a/tests/test_types.py b/tests/test_types.py
index d8d82a517ea9..111116938423 100644
--- a/tests/test_types.py
+++ b/tests/test_types.py
@@ -13,11 +13,35 @@
 # limitations under the License.
 
 from synapse.api.errors import SynapseError
-from synapse.types import RoomAlias, UserID, map_username_to_mxid_localpart
+from synapse.types import (
+    RoomAlias,
+    UserID,
+    get_domain_from_id,
+    get_localpart_from_id,
+    map_username_to_mxid_localpart,
+)
 
 from tests import unittest
 
 
+class IsMineIDTests(unittest.HomeserverTestCase):
+    def test_is_mine_id(self) -> None:
+        self.assertTrue(self.hs.is_mine_id("@user:test"))
+        self.assertTrue(self.hs.is_mine_id("#room:test"))
+        self.assertTrue(self.hs.is_mine_id("invalid:test"))
+
+        self.assertFalse(self.hs.is_mine_id("@user:test\0"))
+        self.assertFalse(self.hs.is_mine_id("@user"))
+
+    def test_two_colons(self) -> None:
+        """Test handling of IDs containing more than one colon."""
+        # The domain starts after the first colon.
+        # These functions must interpret things consistently.
+        self.assertFalse(self.hs.is_mine_id("@user:test:test"))
+        self.assertEqual("user", get_localpart_from_id("@user:test:test"))
+        self.assertEqual("test:test", get_domain_from_id("@user:test:test"))
+
+
 class UserIDTestCase(unittest.HomeserverTestCase):
     def test_parse(self):
         user = UserID.from_string("@1234abcd:test")