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40 lines
5.0 KiB
Markdown
40 lines
5.0 KiB
Markdown
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# system.metrics {#system_tables-metrics}
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Contains metrics which can be calculated instantly, or have a current value. For example, the number of simultaneously processed queries or the current replica delay. This table is always up to date.
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Columns:
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- `metric` ([String](../../sql-reference/data-types/string.md)) — Metric name.
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- `value` ([Int64](../../sql-reference/data-types/int-uint.md)) — Metric value.
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- `description` ([String](../../sql-reference/data-types/string.md)) — Metric description.
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The list of supported metrics you can find in the [src/Common/CurrentMetrics.cpp](https://github.com/ClickHouse/ClickHouse/blob/master/src/Common/CurrentMetrics.cpp) source file of ClickHouse.
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**Example**
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``` sql
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SELECT * FROM system.metrics LIMIT 10
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```
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``` text
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┌─metric─────────────────────┬─value─┬─description──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Query │ 1 │ Number of executing queries │
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│ Merge │ 0 │ Number of executing background merges │
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│ PartMutation │ 0 │ Number of mutations (ALTER DELETE/UPDATE) │
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│ ReplicatedFetch │ 0 │ Number of data parts being fetched from replicas │
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│ ReplicatedSend │ 0 │ Number of data parts being sent to replicas │
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│ ReplicatedChecks │ 0 │ Number of data parts checking for consistency │
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│ BackgroundPoolTask │ 0 │ Number of active tasks in BackgroundProcessingPool (merges, mutations, fetches, or replication queue bookkeeping) │
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│ BackgroundSchedulePoolTask │ 0 │ Number of active tasks in BackgroundSchedulePool. This pool is used for periodic ReplicatedMergeTree tasks, like cleaning old data parts, altering data parts, replica re-initialization, etc. │
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│ DiskSpaceReservedForMerge │ 0 │ Disk space reserved for currently running background merges. It is slightly more than the total size of currently merging parts. │
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│ DistributedSend │ 0 │ Number of connections to remote servers sending data that was INSERTed into Distributed tables. Both synchronous and asynchronous mode. │
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└────────────────────────────┴───────┴──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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```
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**See Also**
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- [system.asynchronous\_metrics](asynchronous_metrics.md#system_tables-asynchronous_metrics) — Contains periodically calculated metrics.
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- [system.events](events.md#system_tables-events) — Contains a number of events that occurred.
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- [system.metric\_log](metric_log.md#system_tables-metric_log) — Contains a history of metrics values from tables `system.metrics` и `system.events`.
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- [Monitoring](../../operations/monitoring.md) — Base concepts of ClickHouse monitoring.
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