TiFlash supports stale read

[hehechen]

Signed-off-by: hehechen awd123456sss@gmail.com

What problem does this PR solve?

Issue Number: close #4483

Problem Summary:

What is changed and how it works?

TiFlash supports stale raed.

1. check safe_ts that if read_index can be skipped.
2. use query_ts, local_query_id, server_id as the MPP query id.

Check List

Tests

• Unit test

• Integration test

• Manual test (add detailed scripts or steps below)
  run CH-benCHmark with stale read
  

• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• CalvinNeo
• SeaRise

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[hehechen]

/run-unit-test

[hehechen]

/run-all-tests

[hehechen]

/run-integration-test

[hehechen]

/run-integration-test

[hehechen]

tiflash/dbms/src/Storages/StorageDisaggregated.cpp

Lines 99 to 102 in fa67119

	::mpp::TaskMeta * dispatch_req_meta = dispatch_req->mutable_meta();
	dispatch_req_meta->set_start_ts(sender_target_task_start_ts);
	dispatch_req_meta->set_task_id(sender_target_task_task_id);
	dispatch_req_meta->set_address(batch_cop_task.store_addr);

StorageDisaggregated::buildDispatchMPPTaskRequest constructs a TaskMeta to send to tiflash storage node, I think you need to update it too.

Done.

[hehechen]

/run-all-tests

[CalvinNeo]

lgtm for learner read part

[SeaRise]

Others LGTM

[hehechen]

/run-all-tests

[SeaRise]

lgtm

[windtalker]

Others LGTM

[hehechen]

/merge

[ti-chi-bot]

@hehechen: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: d4da0a1

[ti-chi-bot]

@hehechen: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

trigger some heavy tests which will not run always when PR updated.

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.