2.8. Setting up Continuous WAL Archiving #
Performing PITR and making backups with the ARCHIVE WAL delivery mode require continuous WAL archiving to be enabled. To set up continuous archiving in the cluster, complete the following steps:
Make sure the wal_level parameter is higher than
minimal.If you are configuring archiving on the primary, archive_mode must be set to
onoralways.Set the archive_command parameter, as follows:
archive_command = '"
install_dir/pg_probackup3" archive-push -B "backup_dir" --instance=instance_name--wal-file-name=%f [ssh_options]'
where install_dir is the installation directory of the pg_probackup3 version you are going to use, backup_dir and instance_name refer to the already initialized backup catalog instance for this database cluster, and SSH options only need to be specified to archive WAL on a remote host. For details about all possible archive-push parameters, see the section archive-push.
The --wal-file-path option provides the path to the WAL file used by the archive-push command. This path can be absolute or relative. An absolute path is used as-is. A relative path is interpreted relative to the current working directory. When invoked via archive_command, Postgres Pro sets the current working directory to PGDATA, so relative paths like pg_wal/... work correctly:
archive_command = 'pg_probackup3 archive-push -B /backup --instance=main --wal-file-path=%p --wal-file-name=%f'
If --wal-file-path is omitted, pg_wal relative to the current working directory is used:
archive_command = 'pg_probackup3 archive-push -B /backup --instance=main --wal-file-name=%f'
Note
When used in restore_command, Postgres Pro substitutes the %p variable for the full path and %f for the file name before calling pg_probackup3, regardless of whether the path is absolute or relative.
Before starting the Postgres Pro server, you can verify that WAL is correctly sent to the archive by running the archive-push command manually from PGDATA:
cd /var/lib/pgsql/data pg_probackup3 archive-push -B /backup --instance=main --wal-file-path=pg_wal/000000010000000000000001 --wal-file-name=000000010000000000000001
Once these steps are complete, you can start making backups in the ARCHIVE WAL mode as well as perform PITR.
You can view the current state of the WAL archive using the show command. For details, see Section 3.3.2.
Note
Instead of using the archive-push command provided by pg_probackup3, you can use any other tool to set up continuous archiving as long as it delivers WAL segments into backup_dir/wal/instance_namegzip, and .gz suffix in filename is mandatory.
Note
Instead of configuring continuous archiving by setting the archive_mode and archive_command parameters, you can opt for using the pg_receivewal utility. In this case, pg_receivewal -D option should point to directorybackup_dir/wal/instance_name