Archiving

archive_mode

Parameter description: Specifies whether to archive WALs.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1 GUC parameters.

NOTICE: When wal_level is set to minimal, the archive_mode parameter is unavailable.

Value range: Boolean

• on indicates that the archiving is enabled.
• off indicates that the archiving is disabled.

Default value: off

archive_command

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

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1 GUC parameters.

NOTICE:

• If both archive_dest and archive_commandare configured, WALs are preferentially saved to the directory specified by archive_dest. The command configured by archive_commanddoes not take effect.

• Any %p in the string is replaced by the absolute path of the file to archive, and any %f is replaced by 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. The following shows the command:

archive_command = 'cp --remove-destination %p /mnt/server/archivedir/%f'

• -remove-destination indicates that files will be overwritten during the archiving.

• If there are multiple archive commands, write them to the shell script file and set archive_commandto the command for executing the script. For example:

  -- Assume that multiple commands are as follows:
  test ! -f dir/%f && cp %p dir/%f
  -- The content of the test.sh script is as follows:
  test ! -f dir/$2 && cp $1 dir/$2
  -- The archive command is as follows:
  archive_command='sh dir/test.sh %p %f'

Value range: a string

Default value: (disabled)

archive_dest

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

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1 GUC parameters.

NOTICE:

• If both archive_dest and archive_commandare configured, WALs are preferentially saved to the directory specified by archive_dest. The command configured by archive_commanddoes not take effect.
• If the string is a relative path, it is relative to the data directory. The following is an example:

archive_dest = '/mnt/server/archivedir/'

Value range: a string

Default value: an empty string

archive_timeout

Parameter description: Specifies the archiving period.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1 GUC parameters.

NOTICE:

• The server is forced to switch to a new WAL segment file when the period specified by this parameter has elapsed since the last file switch.
• Archived files that are closed early due to a forced switch are still of the same length as full files. Therefore, a very short archive_timeout will bloat the archive storage. You are advised to set archive_timeout to 60s.

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

Default value: 0