Archiving

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

• 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.

• The max_xlog_backup_size parameter setting takes effect only when archive_mode is enabled and archive_command is set to NULL.
• The system checks the size of backup WALs in the pg_xlog/backup directory every minute. If the size exceeds the value specified by max_xlog_backup_size, the system deletes the earliest backup WALs until the size is less than the max_xlog_backup_size value × 0.9.

• 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.