Skip to main content
Skip to main content
Edit this page

system.background_schedule_pool_log

Querying in ClickHouse Cloud

The data in this system table is held locally on each node in ClickHouse Cloud. Obtaining a complete view of all data, therefore, requires the clusterAllReplicas function. See here for further details.

The system.background_schedule_pool_log table is created only if the background_schedule_pool_log server setting is specified.

This table contains the history of background schedule pool task executions. Background schedule pools are used for executing periodic tasks such as distributed sends, buffer flushes, and message broker operations.

The system.background_schedule_pool_log table contains the following columns:

  • hostname (LowCardinality(String)) — Hostname of the server executing the query.
  • event_date (Date) — Event date.
  • event_time (DateTime) — Event time.
  • event_time_microseconds (DateTime64) — Event time with microseconds precision.
  • query_id (String) — Identifier of the query associated with the background task (Note, it is not a real query, but just a randomly generated ID for matching logs in system.text_log).
  • database (LowCardinality(String)) — Name of the database.
  • table (LowCardinality(String)) — Name of the table.
  • table_uuid (UUID) — UUID of the table the background task belongs to.
  • log_name (LowCardinality(String)) — Name of the background task.
  • duration_ms (UInt64) — Duration of the task execution in milliseconds.
  • error (UInt16) — The error code of the occurred exception.
  • exception (String) — Text message of the occurred error.

The system.background_schedule_pool_log table is created after the first background task execution.

Example

SELECT * FROM system.background_schedule_pool_log LIMIT 1 FORMAT Vertical;

Row 1:
──────
hostname:                clickhouse.eu-central1.internal
event_date:              2025-12-18
event_time:              2025-12-18 10:30:15
event_time_microseconds: 2025-12-18 10:30:15.123456
query_id:
database:                default
table:                   data
table_uuid:              00000000-0000-0000-0000-000000000000
log_name:                default.data
duration_ms:             42
error:                   0
exception:

See Also