background_schedule_* server settings

These settings configure the ClickHouse server and are autogenerated from ClickHouse source.

background_schedule_pool_initial_size

Initial number of worker threads allocated for each background schedule pool. Each pool grows lazily up to its configured cap (background_schedule_pool_size and friends) when demand exceeds the current set of workers. Lower values reduce startup overhead and idle thread counts; higher values eliminate first-task scheduling latency on busy servers.

background_schedule_pool_log

Contains information about all background tasks that are executed via various background pools.

<background_schedule_pool_log>
    <database>system</database>
    <table>background_schedule_pool_log</table>
    <partition_by>toYYYYMM(event_date)</partition_by>
    <flush_interval_milliseconds>7500</flush_interval_milliseconds>
    <max_size_rows>1048576</max_size_rows>
    <reserved_size_rows>8192</reserved_size_rows>
    <buffer_size_rows_flush_threshold>524288</buffer_size_rows_flush_threshold>
    <flush_on_crash>false</flush_on_crash>
    <!-- Only tasks longer than duration_threshold_milliseconds will be logged. Zero means log everything -->
    <duration_threshold_milliseconds>0</duration_threshold_milliseconds>
</background_schedule_pool_log>

background_schedule_pool_max_parallel_tasks_per_type_ratio

The maximum ratio of threads in the pool that can execute tasks of the same type simultaneously.

background_schedule_pool_size

The cap on the number of threads used to execute lightweight periodic operations for replicated tables, Kafka streaming, DNS cache updates, and similar tasks. Threads are spawned lazily on demand up to this cap, so a server with light background load uses far fewer threads than this number.

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background_schedule_pool_initial_size

background_schedule_pool_log

background_schedule_pool_max_parallel_tasks_per_type_ratio

background_schedule_pool_size

​background_schedule_pool_initial_size

​background_schedule_pool_log

​background_schedule_pool_max_parallel_tasks_per_type_ratio

​background_schedule_pool_size

background_schedule_pool_initial_size

background_schedule_pool_log

background_schedule_pool_max_parallel_tasks_per_type_ratio

background_schedule_pool_size