system.query_thread_log

Contains information about threads that execute queries, for example, thread name, thread start time, duration of query processing.

To start logging:

  1. Configure parameters in the query_thread_log section.
  2. Set log_query_threads to 1.

The flushing period of data is set in flush_interval_milliseconds parameter of the query_thread_log server settings section. To force flushing, use the SYSTEM FLUSH LOGS query.

ClickHouse doesn’t delete data from the table automatically. See Introduction for more details.

Columns:

  • event_date (Date) — The date when the thread has finished execution of the query.
  • event_time (DateTime) — The date and time when the thread has finished execution of the query.
  • event_time_microsecinds (DateTime) — The date and time when the thread has finished execution of the query with microseconds precision.
  • query_start_time (DateTime) — Start time of query execution.
  • query_start_time_microseconds (DateTime64) — Start time of query execution with microsecond precision.
  • query_duration_ms (UInt64) — Duration of query execution.
  • read_rows (UInt64) — Number of read rows.
  • read_bytes (UInt64) — Number of read bytes.
  • written_rows (UInt64) — For INSERT queries, the number of written rows. For other queries, the column value is 0.
  • written_bytes (UInt64) — For INSERT queries, the number of written bytes. For other queries, the column value is 0.
  • memory_usage (Int64) — The difference between the amount of allocated and freed memory in context of this thread.
  • peak_memory_usage (Int64) — The maximum difference between the amount of allocated and freed memory in context of this thread.
  • thread_name (String) — Name of the thread.
  • thread_number (UInt32) — Internal thread ID.
  • thread_id (Int32) — thread ID.
  • master_thread_id (UInt64) — OS initial ID of initial thread.
  • query (String) — Query string.
  • is_initial_query (UInt8) — Query type. Possible values:
    • 1 — Query was initiated by the client.
    • 0 — Query was initiated by another query for distributed query execution.
  • user (String) — Name of the user who initiated the current query.
  • query_id (String) — ID of the query.
  • address (IPv6) — IP address that was used to make the query.
  • port (UInt16) — The client port that was used to make the query.
  • initial_user (String) — Name of the user who ran the initial query (for distributed query execution).
  • initial_query_id (String) — ID of the initial query (for distributed query execution).
  • initial_address (IPv6) — IP address that the parent query was launched from.
  • initial_port (UInt16) — The client port that was used to make the parent query.
  • interface (UInt8) — Interface that the query was initiated from. Possible values:
    • 1 — TCP.
    • 2 — HTTP.
  • os_user (String) — OS’s username who runs clickhouse-client.
  • client_hostname (String) — Hostname of the client machine where the clickhouse-client or another TCP client is run.
  • client_name (String) — The clickhouse-client or another TCP client name.
  • client_revision (UInt32) — Revision of the clickhouse-client or another TCP client.
  • client_version_major (UInt32) — Major version of the clickhouse-client or another TCP client.
  • client_version_minor (UInt32) — Minor version of the clickhouse-client or another TCP client.
  • client_version_patch (UInt32) — Patch component of the clickhouse-client or another TCP client version.
  • http_method (UInt8) — HTTP method that initiated the query. Possible values:
    • 0 — The query was launched from the TCP interface.
    • 1 — GET method was used.
    • 2 — POST method was used.
  • http_user_agent (String) — The UserAgent header passed in the HTTP request.
  • quota_key (String) — The “quota key” specified in the quotas setting (see keyed).
  • revision (UInt32) — ClickHouse revision.
  • ProfileEvents.Names (Array(String)) — Counters that measure different metrics for this thread. The description of them could be found in the table system.events.
  • ProfileEvents.Values (Array(UInt64)) — Values of metrics for this thread that are listed in the ProfileEvents.Names column.

Example

  1.  SELECT * FROM system.query_thread_log LIMIT 1 \G
  1. Row 1:
  2. ──────
  3. event_date:                    2020-09-11
  4. event_time:                    2020-09-11 10:08:17
  5. event_time_microseconds:       2020-09-11 10:08:17.134042
  6. query_start_time:              2020-09-11 10:08:17
  7. query_start_time_microseconds: 2020-09-11 10:08:17.063150
  8. query_duration_ms:             70
  9. read_rows:                     0
  10. read_bytes:                    0
  11. written_rows:                  1
  12. written_bytes:                 12
  13. memory_usage:                  4300844
  14. peak_memory_usage:             4300844
  15. thread_name:                   TCPHandler
  16. thread_id:                     638133
  17. master_thread_id:              638133
  18. query:                         INSERT INTO test1 VALUES
  19. is_initial_query:              1
  20. user:                          default
  21. query_id:                      50a320fd-85a8-49b8-8761-98a86bcbacef
  22. address:                       ::ffff:127.0.0.1
  23. port:                          33452
  24. initial_user:                  default
  25. initial_query_id:              50a320fd-85a8-49b8-8761-98a86bcbacef
  26. initial_address:               ::ffff:127.0.0.1
  27. initial_port:                  33452
  28. interface:                     1
  29. os_user:                       bharatnc
  30. client_hostname:               tower
  31. client_name:                   ClickHouse 
  32. client_revision:               54437
  33. client_version_major:          20
  34. client_version_minor:          7
  35. client_version_patch:          2
  36. http_method:                   0
  37. http_user_agent:               
  38. quota_key:                     
  39. revision:                      54440
  40. ProfileEvents.Names:           ['Query','InsertQuery','FileOpen','WriteBufferFromFileDescriptorWrite','WriteBufferFromFileDescriptorWriteBytes','ReadCompressedBytes','CompressedReadBufferBlocks','CompressedReadBufferBytes','IOBufferAllocs','IOBufferAllocBytes','FunctionExecute','CreatedWriteBufferOrdinary','DiskWriteElapsedMicroseconds','NetworkReceiveElapsedMicroseconds','NetworkSendElapsedMicroseconds','InsertedRows','InsertedBytes','SelectedRows','SelectedBytes','MergeTreeDataWriterRows','MergeTreeDataWriterUncompressedBytes','MergeTreeDataWriterCompressedBytes','MergeTreeDataWriterBlocks','MergeTreeDataWriterBlocksAlreadySorted','ContextLock','RWLockAcquiredReadLocks','RealTimeMicroseconds','UserTimeMicroseconds','SoftPageFaults','OSCPUVirtualTimeMicroseconds','OSWriteBytes','OSReadChars','OSWriteChars']
  41. ProfileEvents.Values:          [1,1,11,11,591,148,3,71,29,6533808,1,11,72,18,47,1,12,1,12,1,12,189,1,1,10,2,70853,2748,49,2747,45056,422,1520]

See Also

  • system.query_log — Description of the query_log system table which contains common information about queries execution.

Original article