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query_metric_log

Contains history of memory and metric values from table system.events for individual queries, periodically flushed to disk.

Once a query starts, data is collected at periodic intervals of query_metric_log_interval milliseconds (which is set to 1000 by default). The data is also collected when the query finishes if the query takes longer than query_metric_log_interval.

Columns:

  • query_id (String) — ID of the query.
  • 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 resolution.

Example

SELECT * FROM system.query_metric_log LIMIT 1 FORMAT Vertical;
Row 1:
──────
query_id:                                                        97c8ba04-b6d4-4bd7-b13e-6201c5c6e49d
hostname:                                                        clickhouse.eu-central1.internal
event_date:                                                      2020-09-05
event_time:                                                      2020-09-05 16:22:33
event_time_microseconds:                                         2020-09-05 16:22:33.196807
memory_usage:                                                    313434219
peak_memory_usage:                                               598951986
ProfileEvent_Query:                                              0
ProfileEvent_SelectQuery:                                        0
ProfileEvent_InsertQuery:                                        0
ProfileEvent_FailedQuery:                                        0
ProfileEvent_FailedSelectQuery:                                  0
...

See also