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latency_log

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.

Contains history of all latency buckets, periodically 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) — Event time with microseconds resolution.

Example

SELECT * FROM system.latency_log LIMIT 1 FORMAT Vertical;
Row 1:
──────
hostname:                                              clickhouse.eu-central1.internal
event_date:                                            2024-09-19
event_time:                                            2024-09-19 17:09:17
event_time_microseconds:                               2024-09-19 17:09:17.712477
LatencyEvent_S3FirstByteReadAttempt1Microseconds:      [278,278,278,278,278,278,278,278,278,278,278,278,278,278,278,278]
LatencyEvent_S3FirstByteWriteAttempt1Microseconds:     [1774,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776]
LatencyEvent_S3FirstByteReadAttempt2Microseconds:      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
LatencyEvent_S3FirstByteWriteAttempt2Microseconds:     [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
LatencyEvent_S3FirstByteReadAttemptNMicroseconds:      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
LatencyEvent_S3FirstByteWriteAttemptNMicroseconds:     [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
LatencyEvent_S3ReadConnectMicroseconds:                [1,1,1,1,1,1,1,1,1,1]
LatencyEvent_S3WriteConnectMicroseconds:               [329,362,362,363,363,363,363,363,363,363]
LatencyEvent_DiskS3FirstByteReadAttempt1Microseconds:  [278,278,278,278,278,278,278,278,278,278,278,278,278,278,278,278]
LatencyEvent_DiskS3FirstByteWriteAttempt1Microseconds: [1774,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776,1776]
LatencyEvent_DiskS3FirstByteReadAttempt2Microseconds:  [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
LatencyEvent_DiskS3FirstByteWriteAttempt2Microseconds: [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
LatencyEvent_DiskS3FirstByteReadAttemptNMicroseconds:  [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
LatencyEvent_DiskS3FirstByteWriteAttemptNMicroseconds: [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
LatencyEvent_DiskS3ReadConnectMicroseconds:            [1,1,1,1,1,1,1,1,1,1]
LatencyEvent_DiskS3WriteConnectMicroseconds:           [329,362,362,363,363,363,363,363,363,363]

See also