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system.background_schedule_pool

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Description

Contains information about tasks in background schedule pools. Background schedule pools are used for executing periodic tasks such as distributed sends, buffer flushes, message broker operations, streaming queries background jobs, and Iceberg table metadata refresh.

Columns

  • pool (String) — Pool name. Possible values: schedule (general purpose schedule pool), buffer_flush (pool for flushing Buffer table data), distributed (pool for distributed table operations), message_broker (pool for message broker operations), streaming (pool for streaming queries background jobs), iceberg (pool for Iceberg table metadata refresh).
  • database (String) — Database name.
  • table (String) — Table name.
  • table_uuid (UUID) — Table UUID.
  • query_id (String) — Query ID (if executing now). Note: this is not a real query, but a randomly generated ID for matching logs in system.text_log.
  • elapsed_ms (UInt64) — Task execution time (if executing now).
  • log_name (String) — Log name for the task.
  • deactivated (UInt8) — Whether the task is deactivated (always false, since deactivated tasks are removed from the pool).
  • scheduled (UInt8) — Whether the task is scheduled for execution.
  • delayed (UInt8) — Whether the task is scheduled with delay.
  • executing (UInt8) — Whether the task is currently executing.

Example

Querysql
SELECT * FROM system.background_schedule_pool LIMIT 5 FORMAT Vertical;
Responsetext
Row 1:
──────
pool:        distributed
database:    default
table:       data
table_uuid:  00000000-0000-0000-0000-000000000000
query_id:
elapsed_ms:  0
log_name:    BackgroundJobsAssignee:DataProcessing
deactivated: 0
scheduled:   1
delayed:     0
executing:   0

See also

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