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5.1 KiB
system.metrics
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.
Columns:
metric(String) — Metric name.value(Int64) — Metric value.description(String) — Metric description.
The list of supported metrics you can find in the src/Common/CurrentMetrics.cpp source file of ClickHouse.
Example
SELECT * FROM system.metrics LIMIT 10
┌─metric─────────────────────┬─value─┬─description──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ Query │ 1 │ Number of executing queries │
│ Merge │ 0 │ Number of executing background merges │
│ PartMutation │ 0 │ Number of mutations (ALTER DELETE/UPDATE) │
│ ReplicatedFetch │ 0 │ Number of data parts being fetched from replicas │
│ ReplicatedSend │ 0 │ Number of data parts being sent to replicas │
│ ReplicatedChecks │ 0 │ Number of data parts checking for consistency │
│ BackgroundPoolTask │ 0 │ Number of active tasks in BackgroundProcessingPool (merges, mutations, fetches, or replication queue bookkeeping) │
│ 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. │
│ DiskSpaceReservedForMerge │ 0 │ Disk space reserved for currently running background merges. It is slightly more than the total size of currently merging parts. │
│ DistributedSend │ 0 │ Number of connections to remote servers sending data that was INSERTed into Distributed tables. Both synchronous and asynchronous mode. │
└────────────────────────────┴───────┴──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
See Also
- system.asynchronous_metrics — Contains periodically calculated metrics.
- system.events — Contains a number of events that occurred.
- system.metric_log — Contains a history of metrics values from tables
system.metricsиsystem.events. - Monitoring — Base concepts of ClickHouse monitoring.