Re: "Resurrected" data files - problem? - Mailing list pgsql-general

From Peter Childs
Subject Re: "Resurrected" data files - problem?
Date
Msg-id a2de01dd0711080431i55040264tf35cd38aca56bab4@mail.gmail.com
Whole thread Raw
In response to "Resurrected" data files - problem?  ("Albe Laurenz" <laurenz.albe@wien.gv.at>)
Responses Re: "Resurrected" data files - problem?  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: "Resurrected" data files - problem?  ("Albe Laurenz" <laurenz.albe@wien.gv.at>)
List pgsql-general


On 08/11/2007, Albe Laurenz <laurenz.albe@wien.gv.at> wrote:
We use a tape backup software that does "incremental backups"
as follows:

- In a full backup, all files are backed up.
- In an incremental backup, only the files with modification
  date after the last backup are backed up.

Now when such a backup is restored, you first have to restore
the full backup, and then the incremental backup.

The problem is that files which were deleted between the full
and the incremental backup will get "resurrected" after such a
restore.

So if we perform our database backups with incremental
backups as described above, we could end up with additional
files after the restore, because PostgreSQL files can get
deleted (e.g. during DROP TABLE or TRUNCATE TABLE).

My question is:

Could such "resurrected" files (data files, files in
pg_xlog, pg_clog or elsewhere) cause a problem for the database
(other than the obvious one that there may be unnecessary files
about that consume disk space)?


This will not work at all.

Try re-reading the instructions on backup in the manual.

oh and always, always, always test your backup works before you actually need it!

Peter Childs

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