2020-06-18 08:24:31 +00:00
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# system.metric\_log {#system_tables-metric_log}
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Contains history of metrics values from tables `system.metrics` and `system.events`, periodically flushed to disk.
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To turn on metrics history collection on `system.metric_log`, create `/etc/clickhouse-server/config.d/metric_log.xml` with following content:
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``` xml
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<yandex>
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<metric_log>
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<database>system</database>
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<table>metric_log</table>
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<flush_interval_milliseconds>7500</flush_interval_milliseconds>
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<collect_interval_milliseconds>1000</collect_interval_milliseconds>
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</metric_log>
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</yandex>
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```
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**Example**
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``` sql
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SELECT * FROM system.metric_log LIMIT 1 FORMAT Vertical;
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```
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``` text
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Row 1:
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──────
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event_date: 2020-02-18
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event_time: 2020-02-18 07:15:33
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milliseconds: 554
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ProfileEvent_Query: 0
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ProfileEvent_SelectQuery: 0
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ProfileEvent_InsertQuery: 0
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ProfileEvent_FileOpen: 0
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ProfileEvent_Seek: 0
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ProfileEvent_ReadBufferFromFileDescriptorRead: 1
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ProfileEvent_ReadBufferFromFileDescriptorReadFailed: 0
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ProfileEvent_ReadBufferFromFileDescriptorReadBytes: 0
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ProfileEvent_WriteBufferFromFileDescriptorWrite: 1
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ProfileEvent_WriteBufferFromFileDescriptorWriteFailed: 0
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ProfileEvent_WriteBufferFromFileDescriptorWriteBytes: 56
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...
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CurrentMetric_Query: 0
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CurrentMetric_Merge: 0
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CurrentMetric_PartMutation: 0
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CurrentMetric_ReplicatedFetch: 0
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CurrentMetric_ReplicatedSend: 0
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CurrentMetric_ReplicatedChecks: 0
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...
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```
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**See also**
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2020-07-09 15:10:35 +00:00
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- [system.asynchronous\_metrics](../../operations/system-tables/asynchronous_metrics.md#system_tables-asynchronous_metrics) — Contains periodically calculated metrics.
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- [system.events](../../operations/system-tables/events.md#system_tables-events) — Contains a number of events that occurred.
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- [system.metrics](../../operations/system-tables/metrics.md#system_tables-metrics) — Contains instantly calculated metrics.
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2020-06-18 08:24:31 +00:00
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- [Monitoring](../../operations/monitoring.md) — Base concepts of ClickHouse monitoring.
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