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2.7 KiB
2.7 KiB
slug |
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/en/operations/system-tables/query_metric_log |
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
- query_metric_log setting — Enabling and disabling the setting.
- query_metric_log_interval
- system.asynchronous_metrics — Contains periodically calculated metrics.
- system.events — Contains a number of events that occurred.
- system.metrics — Contains instantly calculated metrics.
- Monitoring — Base concepts of ClickHouse monitoring.