Unable to connect to a clickhouse server without default database

[v4run]

Describe the bug

When trying to connect to a clickhouse server without default database, Code: 81. DB::Exception is raised.

Steps to reproduce

1. Drop database default
2. Connect to clickhouse server

Expected behaviour

Connection succeeds

Code example

import clickhouse_connect

clickhouse_connect.get_client(host='clickhouse-without-default')

clickhouse-connect and/or ClickHouse server logs

Code: 81. DB::Exception: Database default doesn't exist. (UNKNOWN_DATABASE) (version 22.12.3.5 (official build))

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python3.11/site-packages/clickhouse_connect/__init__.py", line 8, in get_client
    return create_client(**kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/clickhouse_connect/driver/__init__.py", line 107, in create_client
    return HttpClient(interface, host, port, username, password, database, settings=settings, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/clickhouse_connect/driver/httpclient.py", line 139, in __init__
    super().__init__(database=database,
  File "/usr/local/lib/python3.11/site-packages/clickhouse_connect/driver/client.py", line 68, in __init__
    server_settings = self.query(f'SELECT name, value, {readonly} as readonly FROM system.settings LIMIT 10000')
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/clickhouse_connect/driver/client.py", line 188, in query
    return self._query_with_context(query_context)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/clickhouse_connect/driver/httpclient.py", line 208, in _query_with_context
    response = self._raw_request(body,
               ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/clickhouse_connect/driver/httpclient.py", line 407, in _raw_request
    self._error_handler(response)
  File "/usr/local/lib/python3.11/site-packages/clickhouse_connect/driver/httpclient.py", line 332, in _error_handler
    raise OperationalError(err_str) if retried else DatabaseError(err_str) from None
clickhouse_connect.driver.exceptions.DatabaseError: :HTTPDriver for http://clickhouse:8123 returned response code 404)
 Code: 81. DB::Exception: Database default doesn't exist. (UNKNOWN_DATABASE) (version 22.12.3.5 (official build))

Configuration

Environment

• clickhouse-connect version: 0.6.3
• Python version: 3.11.4
• Operating system: Debian GNU/Linux 12 (bookworm) (docker container)

ClickHouse server

• ClickHouse Server version: 22.12.3.5

Sample docker-compose.yaml file to recreate the issue

version: "3"
services:
  clickhouse:
    image: clickhouse/clickhouse-server:22.12.3.5

  job:
    image: python:3
    entrypoint: ["bash", "-c"]
    depends_on:
      - clickhouse
    command: |
      "pip install clickhouse-connect
       until [ \"$$STATUS\" = \"Ok.\" ]; do STATUS=$(curl -s 'http://clickhouse:8123'); sleep 2; done
       echo 'DROP DATABASE default' | curl -s 'http://clickhouse:8123' --data-binary @-
       python3 -c \"import clickhouse_connect; clickhouse_connect.get_client(host='clickhouse', database='system')\""

[genzgd]

Does it work if you set the database argument to a valid database or None?

[v4run]

Nope. I tried setting it to 'system' and None.

[genzgd]

So the problem is the ClickHouse function currentDatabase() returns default even if the default database doesn't exist. I'll have to work around that behavior on initialization.

[pkit]

So the problem is the ClickHouse function currentDatabase() returns default even if the default database doesn't exist.

No, the problem is that @v4run didn't set default_database in the server settings after dropping default database. And did not restart the server.
I.e. it's not a bug.