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.

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

Both synchronous standby machine and asynchronous standby machine can start archiving, and the way to start archiving is the same as that of single machine. Just set the archive_mode to on and set the correct archive_ dest or archive_ command. Note: if the most_available is not on and there is a synchronous standby disconnected from the host, the primary will be unable to send the location of the archive to the standby due to traffic congestion, resulting in archive failure.

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.

NOTICE:

• If both **archive_dest **and **archive_command **are configured, WALs are preferentially saved to the directory specified by archive_dest. The command configured by **archive_command **does 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 command example is as follows:

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_command **to the command for executing the script. The command example is as follows:

-- 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.

NOTICE:

• If both **archive_dest **and **archive_command **are configured, WALs are preferentially saved to the directory specified by archive_dest. The command configured by **archive_command **does 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: empty

archive_timeout

Parameter description: Specifies the archiving period.

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

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 1073741823. The unit is s. 0 indicates that archiving timeout is disabled.

Default value: 0