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

# system.histogram_metric_log

<Info>
  **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](/reference/system-tables/overview#system-tables-in-clickhouse-cloud) for further details.
</Info>

<h2 id="description">
  Description
</h2>

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

<h2 id="columns">
  Columns
</h2>

* `hostname` ([LowCardinality(String)](/reference/data-types/lowcardinality)) — Hostname of the server executing the query.
* `event_date` ([Date](/reference/data-types/date)) — Event date.
* `event_time` ([DateTime](/reference/data-types/datetime)) — Event time.
* `event_time_microseconds` ([DateTime64(6)](/reference/data-types/datetime64)) — Event time with microseconds resolution.
* `metric` ([LowCardinality(String)](/reference/data-types/lowcardinality)) — Metric name.
* `labels` ([Map(LowCardinality(String), LowCardinality(String))](/reference/data-types/map)) — Metric labels.
* `histogram` ([Map(Float64, UInt64)](/reference/data-types/map)) — Cumulative histogram: maps bucket upper bound to number of observations ≤ that bound; includes +inf as the final bucket.
* `count` ([UInt64](/reference/data-types/int-uint)) — Total number of observations, equals histogram\[+inf].
* `sum` ([Float64](/reference/data-types/float)) — Sum of all observed values.

<h2 id="example">
  Example
</h2>

```sql theme={null}
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;
```

<h2 id="see-also">
  See Also
</h2>

* [system.histogram\_metrics](/reference/system-tables/histogram_metrics) — Live histogram metrics.
* [system.metric\_log](/reference/system-tables/metric_log) — History of `system.metrics` and `system.events`.