Knowledge Base

The new setting `allow_asynchronous_read_from_io_pool_for_merge_tree` allows the number of reading threads (streams) to be higher than the number of threads in the rest of the query execution pipeline.

Learn how to define settings in ClickHouse for individual queries, client sessions, or specific users using `SET` and `ALTER USER` commands.

Learn how to use `ON CLUSTER` and `clusterAllReplicas` to execute SYSTEM statements and queries across all nodes in a ClickHouse Cloud service.

Learn how to use filtered aggregates in ClickHouse with `-If` and `-Distinct` aggregate combinators to simplify query syntax and enhance analytics.

Learn how to configure the Global Thread pool in ClickHouse by adjusting settings like `max_thread_pool_size`, `thread_pool_queue_size`, and `max_thread_pool_free_size`.

Learn how to use the `skip_check_for_incorrect_settings` option to allow ClickHouse to start even when user-level settings are specified incorrectly.

Learn how to capture server logs at the client level, even with different log settings, using the `send_logs_level` client setting.

A query to compare metrics between two queries in ClickHouse.

Learn how to use CSP marketplaces to subscribe to ClickHouse Cloud.

Learn how to resolve ingest failures caused by stricter grant checking introduced in ClickHouse 23.9 for tables using `async_inserts`. Update grants to fix errors.