> ## Documentation Index
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# atoti_directquery_clickhouse.ConnectionConfig

### *final class* atoti\_directquery\_clickhouse.ConnectionConfig

Config to connect to a ClickHouse database.

<Callout icon="link">
  **See also**:
  [`atoti_directquery_snowflake.ConnectionConfig`](./atoti_directquery_snowflake.connection_config#atoti_directquery_snowflake.ConnectionConfig) for an example.
</Callout>

#### column\_clustered\_queries *: 'all' | 'feeding'* *= 'feeding'*

Control which queries will use clustering columns.

#### feeding\_query\_timeout *: Duration* *= datetime.timedelta(seconds=3600)*

Timeout for queries performed on the external database during feeding phases.

The feeding phases are:

* the initial load to feed [`aggregate_providers`](./atoti.Cube.aggregate_providers#atoti.Cube.aggregate_providers) and [`hierarchies`](./atoti.Cube.hierarchies#atoti.Cube.hierarchies);
* the refresh operations.

#### lookup\_mode *: 'allow' | 'warn' | 'deny'* *= 'warn'*

Whether lookup queries on the external database are allowed.

Lookup can be very slow and expensive as the database may not enforce primary keys.

#### max\_sub\_queries *: Annotated\[[int](https://docs.python.org/3/library/functions.html#int), Field(gt=0)]* *= 500*

Maximum number of sub queries performed when splitting a query into multi-step queries.

#### password *: [str](https://docs.python.org/3/library/stdtypes.html#str) | [None](https://docs.python.org/3/library/constants.html#None)* *= None*

The password to connect to the database.

Passing it in this separate attribute prevents it from being logged alongside the connection string.

If `None`, a password is expected to be present in [`url`](#atoti_directquery_clickhouse.ConnectionConfig.url).

#### query\_timeout *: Duration* *= datetime.timedelta(seconds=300)*

Timeout for queries performed on the external database outside feeding phases.

#### url *: [str](https://docs.python.org/3/library/stdtypes.html#str)*

The connection string.

The pattern is: `(clickhouse|ch):(https|http|...)://login:password@host:port/database?prop=value`.
For example: `"clickhouse:https://user:password@localhost:8123/mydb"`.
When a part is missing, its default value will be used.