pg_archivecleanup

pg_archivecleanup — 清理 PostgreSQL WAL 歸檔檔案

語法

pg_archivecleanup [option...] archivelocation oldestkeptwalfile

說明

pg_archivecleanup 設計用於 archive_cleanup_command,以在作為備用伺服器執行時清除 WAL 檔案存檔(請參閱第 26.2 節)。pg_archivecleanup 也可以作為獨立程序來清理 WAL 歸檔檔案。

To configure a standby server to use pg_archivecleanup, put this into its postgresql.conf configuration file:

archive_cleanup_command = 'pg_archivecleanup archivelocation %r'

where archivelocation is the directory from which WAL segment files should be removed.

When used within archive_cleanup_command, all WAL files logically preceding the value of the %r argument will be removed from archivelocation. This minimizes the number of files that need to be retained, while preserving crash-restart capability. Use of this parameter is appropriate if the archivelocation is a transient staging area for this particular standby server, but not when the archivelocation is intended as a long-term WAL archive area, or when multiple standby servers are recovering from the same archive location.

When used as a standalone program all WAL files logically preceding the oldestkeptwalfile will be removed from archivelocation. In this mode, if you specify a .partial or .backup file name, then only the file prefix will be used as the oldestkeptwalfile. This treatment of .backup file name allows you to remove all WAL files archived prior to a specific base backup without error. For example, the following example will remove all files older than WAL file name 000000010000003700000010:

pg_archivecleanup -d archive 000000010000003700000010.00000020.backup
pg_archivecleanup: keep WAL file "archive/000000010000003700000010" and later
pg_archivecleanup: removing file "archive/00000001000000370000000F"
pg_archivecleanup: removing file "archive/00000001000000370000000E"

pg_archivecleanup assumes that archivelocation is a directory readable and writable by the server-owning user.

Options

pg_archivecleanup accepts the following command-line arguments:

-d

Print lots of debug logging output on stderr.

-n

Print the names of the files that would have been removed on stdout (performs a dry run).

-V --version

Print the pg_archivecleanup version and exit.

-x extension

Provide an extension that will be stripped from all file names before deciding if they should be deleted. This is typically useful for cleaning up archives that have been compressed during storage, and therefore have had an extension added by the compression program. For example:

-x .gz.-? --help

Show help about pg_archivecleanup command line arguments, and exit.

Environment

The environment variable PG_COLOR specifies whether to use color in diagnostic messages. Possible values are always, auto and never.

Notes

pg_archivecleanup is designed to work with PostgreSQL 8.0 and later when used as a standalone utility, or with PostgreSQL 9.0 and later when used as an archive cleanup command.

pg_archivecleanup is written in C and has an easy-to-modify source code, with specifically designated sections to modify for your own needs

Examples

On Linux or Unix systems, you might use:

archive_cleanup_command = 'pg_archivecleanup -d /mnt/standby/archive %r 2>>cleanup.log'

where the archive directory is physically located on the standby server, so that the archive_command is accessing it across NFS, but the files are local to the standby. This will:

  • produce debugging output in cleanup.log

  • remove no-longer-needed files from the archive directory

參閱

pg_standby