system.histogram_metric_log

System table containing periodic snapshots of histogram metrics, flushed to disk.

Querying in ClickHouse Cloud

The data in this system table is held locally on each node in ClickHouse Cloud. Obtaining a complete view of all data, therefore, requires the clusterAllReplicas function. See here for further details.

Description

History of system.histogram_metrics. Snapshot taken every collect_interval_milliseconds, flushed to disk.

Columns

• hostname (LowCardinality(String)) — Hostname of the server executing the query.
• event_date (Date) — Event date.
• event_time (DateTime) — Event time.
• event_time_microseconds (DateTime64(6)) — Event time with microseconds resolution.
• metric (LowCardinality(String)) — Metric name.
• labels (Map(LowCardinality(String), LowCardinality(String))) — Metric labels.
• histogram (Map(Float64, UInt64)) — Cumulative histogram: maps bucket upper bound to number of observations ≤ that bound; includes +inf as the final bucket.
• count (UInt64) — Total number of observations, equals histogram[+inf].
• sum (Float64) — Sum of all observed values.

Example

SELECT event_time, metric, labels, histogram
FROM system.histogram_metric_log
WHERE metric = 'keeper_response_time_ms'
ORDER BY event_time DESC
LIMIT 1
FORMAT Vertical;

See Also

• system.histogram_metrics — Live histogram metrics.
• system.metric_log — History of system.metrics and system.events.