ClickHouse/docs/en/operations/system-tables/metric_log.md

system.metric_log

Contains history of metrics values from tables system.metrics and system.events, periodically flushed to disk. To turn on metrics history collection on system.metric_log, create /etc/clickhouse-server/config.d/metric_log.xml with following content:

<yandex>
    <metric_log>
        <database>system</database>
        <table>metric_log</table>
        <flush_interval_milliseconds>7500</flush_interval_milliseconds>
        <collect_interval_milliseconds>1000</collect_interval_milliseconds>
    </metric_log>
</yandex>

Example

SELECT * FROM system.metric_log LIMIT 1 FORMAT Vertical;

Row 1:
──────
event_date:                                                      2020-09-05
event_time:                                                      2020-09-05 16:22:33
event_time_microseconds:                                         2020-09-05 16:22:33.196807
milliseconds:                                                    196
ProfileEvent_Query:                                              0
ProfileEvent_SelectQuery:                                        0
ProfileEvent_InsertQuery:                                        0
ProfileEvent_FailedQuery:                                        0
ProfileEvent_FailedSelectQuery:                                  0
...
...
CurrentMetric_Revision:                                          54439
CurrentMetric_VersionInteger:                                    20009001
CurrentMetric_RWLockWaitingReaders:                              0
CurrentMetric_RWLockWaitingWriters:                              0
CurrentMetric_RWLockActiveReaders:                               0
CurrentMetric_RWLockActiveWriters:                               0
CurrentMetric_GlobalThread:                                      74
CurrentMetric_GlobalThreadActive:                                26
CurrentMetric_LocalThread:                                       0
CurrentMetric_LocalThreadActive:                                 0
CurrentMetric_DistributedFilesToInsert:                          0

See also

• 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.

Original article