Help Center/ GaussDB(DWS)/ Developer Guide/ Standard data warehouse (8.3.0.x)/ GUC Parameters of the GaussDB(DWS) Database/ Write Ahead Logs/ Archiving
Updated on 2024-11-05 GMT+08:00
View PDF
Share

Archiving

archive_mode

Parameter description: When archive_mode is enabled, completed WAL segments are sent to archive storage by setting archive_command.

Type: SIGHUP

Value range: Boolean

  • on: The archiving is enabled.
  • off: The archiving is disabled.

Default value: off

When wal_level is set to minimal, archive_mode cannot be used.

archive_command

Parameter description: Specifies the command used to archive WALs set by the administrator. You are advised to set the archive log path to an absolute path.

Type: SIGHUP

Value range: a string

Default value: (disabled)

  • Any %p in the string is replaced with the absolute path of the file to archive, and any %f is replaced with only the file name. (The relative path is relative to the data directory.) Use %% to embed an actual % character in the command.
  • This command returns zero only if it succeeds. Example: 
    1
2
    		 
    archive_command = 'cp --remove-destination %p /mnt/server/archivedir/%f' 
archive_command = 'copy %p /mnt/server/archivedir/%f'  # Windows
  • --remove-destination indicates that files will be overwritten during the archiving.
  • When archive_mode is set to on or not specified, a backup folder will be created in the pg_xlog directory and WALs will be compressed and copied to the pg_xlog/backup directory.

archive_timeout

Parameter description: Specifies the archiving period.

Type: SIGHUP

Value range: an integer ranging from 0 to INT_MAX. The unit is second. 0 indicates that archiving timeout is disabled.

Default value: 0

  • The server is forced to switch to a new WAL segment file with the period specified by this parameter.
  • Archived files that are closed early due to a forced switch are still of the same length as completely full files. Therefore, a very short archive_timeout will bloat the archive storage. You are advised to set archive_timeout to 60s.
Parent topic: Write Ahead Logs