Should *.backup files ever be removed from pg_xlog?

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Should *.backup files ever be removed from pg_xlog?

Bruce Momjian-2
When you do a pg_start_backup()/pg_stop_backup(), the *.backup files
created in pg_xlog are never deleted.  Is that intended?

        $ lf /u/pg/data/pg_xlog/
        000000010000000000000000.0034C96C.backup        000000010000000000000004
        000000010000000000000000.0034C9AC.backup        000000010000000000000005
        000000010000000000000002                        000000010000000000000006
        000000010000000000000003                        archive_status/

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Re: Should *.backup files ever be removed from pg_xlog?

Tom Lane-2
Bruce Momjian <[hidden email]> writes:
> When you do a pg_start_backup()/pg_stop_backup(), the *.backup files
> created in pg_xlog are never deleted.  Is that intended?

Yes.  See the documentation.  DBAs can delete 'em if they feel like,
but I don't see a strong argument for automatically removing 'em.
They aren't actually large ...

                        regards, tom lane

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Re: Should *.backup files ever be removed from pg_xlog?

Bruce Momjian-2
Tom Lane wrote:
> Bruce Momjian <[hidden email]> writes:
> > When you do a pg_start_backup()/pg_stop_backup(), the *.backup files
> > created in pg_xlog are never deleted.  Is that intended?
>
> Yes.  See the documentation.  DBAs can delete 'em if they feel like,
> but I don't see a strong argument for automatically removing 'em.
> They aren't actually large ...

I don't see anywhere in the documentation where we say you can get rid
of them.  I see this:

        For example, if the starting WAL file is 0000000100001234000055CD the
        backup history file will be named something like
        0000000100001234000055CD.007C9330.backup. (The second number in the file
        name stands for an exact position within the WAL file, and can
        ordinarily be ignored.) Once you have safely archived the file system
        backup and the WAL segment files used during the backup (as specified in
        the backup history file), all archived WAL segments with names
        numerically less are no longer needed to recover the file system backup
        and may be deleted. However, you should consider keeping several backup
        sets to be absolutely certain that you are can recover your data. Keep
        in mind that only completed WAL segment files are archived, so there
        will be delay between running pg_stop_backup and the archiving of all
        WAL segment files needed to make the file system backup consistent.

The "all archived WAL segments with names numerically less are no longer
needed" I assume is talking about files in the archive location, not
pg_xlog.  Does this need clarifying?

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  Bruce Momjian                        |  http://candle.pha.pa.us
  [hidden email]               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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