system.processes

This system table is used for implementing the SHOW PROCESSLIST query.

Columns:

  • user (String) – The user who made the query. Keep in mind that for distributed processing, queries are sent to remote servers under the default user. The field contains the username for a specific query, not for a query that this query initiated.
  • address (String) – The IP address the request was made from. The same for distributed processing. To track where a distributed query was originally made from, look at system.processes on the query requestor server.
  • elapsed (Float64) – The time in seconds since request execution started.
  • rows_read (UInt64) – The number of rows read from the table. For distributed processing, on the requestor server, this is the total for all remote servers.
  • bytes_read (UInt64) – The number of uncompressed bytes read from the table. For distributed processing, on the requestor server, this is the total for all remote servers.
  • total_rows_approx (UInt64) – The approximation of the total number of rows that should be read. For distributed processing, on the requestor server, this is the total for all remote servers. It can be updated during request processing, when new sources to process become known.
  • memory_usage (UInt64) – Amount of RAM the request uses. It might not include some types of dedicated memory. See the max_memory_usage setting.
  • query (String) – The query text. For INSERT, it doesn’t include the data to insert.
  • query_id (String) – Query ID, if defined.
  1. :) SELECT * FROM system.processes LIMIT 10 FORMAT Vertical;
  1. Row 1:
  2. ──────
  3. is_initial_query:     1
  4. user:                 default
  5. query_id:             35a360fa-3743-441d-8e1f-228c938268da
  6. address:              ::ffff:172.23.0.1
  7. port:                 47588
  8. initial_user:         default
  9. initial_query_id:     35a360fa-3743-441d-8e1f-228c938268da
  10. initial_address:      ::ffff:172.23.0.1
  11. initial_port:         47588
  12. interface:            1
  13. os_user:              bharatnc
  14. client_hostname:      tower
  15. client_name:          ClickHouse 
  16. client_revision:      54437
  17. client_version_major: 20
  18. client_version_minor: 7
  19. client_version_patch: 2
  20. http_method:          0
  21. http_user_agent:      
  22. quota_key:            
  23. elapsed:              0.000582537
  24. is_cancelled:         0
  25. read_rows:            0
  26. read_bytes:           0
  27. total_rows_approx:    0
  28. written_rows:         0
  29. written_bytes:        0
  30. memory_usage:         0
  31. peak_memory_usage:    0
  32. query:                SELECT * from system.processes LIMIT 10 FORMAT Vertical;
  33. thread_ids:           [67]
  34. ProfileEvents.Names:  ['Query','SelectQuery','ReadCompressedBytes','CompressedReadBufferBlocks','CompressedReadBufferBytes','IOBufferAllocs','IOBufferAllocBytes','ContextLock','RWLockAcquiredReadLocks']
  35. ProfileEvents.Values: [1,1,36,1,10,1,89,16,1]
  36. Settings.Names:       ['use_uncompressed_cache','load_balancing','log_queries','max_memory_usage']
  37. Settings.Values:      ['0','in_order','1','10000000000']
  39. 1 rows in set. Elapsed: 0.002 sec.

Original article