База знаний

Resolve the TOO_MANY_PARTS error in ClickHouse during an `INSERT...SELECT` by tuning expert-level settings for larger blocks and increasing partition thresholds.

Learn how to create a ClickHouse dictionary using string keys and values from a MergeTree table as the source, with examples of setup and usage.

Understand the key differences between official ClickHouse builds and 3rd-party builds, including updates, compatibility, and security considerations.

Learn how to check if query cache is being utilized in ClickHouse using `clickhouse-client` trace logs or SQL commands.

Learn how to use the `FORMAT Null` option in ClickHouse to measure query processing time without returning any rows to the client.

Learn how to start, stop, and resume a ClickHouse Cloud service using API endpoints and cURL commands.

Learn how to resolve Docker capability warnings for `CAP_IPC_LOCK` and `CAP_SYS_NICE` when running ClickHouse in a container.

Learn how to use the `system.query_log` table to find the most memory-intensive queries in ClickHouse, with examples for clustered and standalone setups.

Learn about automatic schema migration tools for ClickHouse and how to manage changing database schemas over time.

Monitor the number of active or queued mutations in ClickHouse, especially when performing `ALTER` or `UPDATE` operations. Use the `system.mutations` table for tracking mutations.