Re: [GENERAL] "Resurrected" data files - problem?

From: Tom Lane <tgl(at)sss.pgh.pa.us>
Date: Thu Nov 08 2007 - 10:39:06 EST

"Peter Childs" <peterachilds@gmail.com> writes:

> On 08/11/2007, Albe Laurenz  wrote:

>> 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).
>>
>> 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.

To be more specific: the resurrected files aren't the problem; offhand I see no reason they'd create any issue beyond wasted disk space. The problem is version skew between files that were backed up at slightly different times, leading to inconsistency.

You could make this work if you shut down Postgres whenever you are taking a backup, but as a means for backing up a live database it indeed won't work at all.

                        regards, tom lane

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TIP 6: explain analyze is your friend Received on Thu Nov 8 11:51:06 2007