system.asynchronous_metric_log

System table containing historical values for system.asynchronous_metrics, which are saved once per time interval (one second by default)

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

Contains the historical values for system.asynchronous_metrics, which are saved once per time interval (one second by default). Enabled by default.

Columns

• hostname (LowCardinality(String)) — Hostname of the server executing the query.
• event_date (Date) — Event date.
• event_time (DateTime) — Event time.
• metric (String) — Metric name.
• value (Float64) — Metric value.

Example

SELECT * FROM system.asynchronous_metric_log LIMIT 3 \G

Row 1:
──────
hostname:   clickhouse.eu-central1.internal
event_date: 2023-11-14
event_time: 2023-11-14 14:39:07
metric:     AsynchronousHeavyMetricsCalculationTimeSpent
value:      0.001

Row 2:
──────
hostname:   clickhouse.eu-central1.internal
event_date: 2023-11-14
event_time: 2023-11-14 14:39:08
metric:     AsynchronousHeavyMetricsCalculationTimeSpent
value:      0

Row 3:
──────
hostname:   clickhouse.eu-central1.internal
event_date: 2023-11-14
event_time: 2023-11-14 14:39:09
metric:     AsynchronousHeavyMetricsCalculationTimeSpent
value:      0

See Also

• asynchronous_metric_log setting — Enabling and disabling the setting.
• system.asynchronous_metrics — Contains metrics, calculated periodically in the background.
• system.metric_log — Contains history of metrics values from tables system.metrics and system.events, periodically flushed to disk.