Re: point in time recovery and moving datafiles online - Mailing list pgsql-hackers

From Tom Lane
Subject Re: point in time recovery and moving datafiles online
Date
Msg-id 16520.1014388340@sss.pgh.pa.us
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In response to Re: point in time recovery and moving datafiles online  ("Zeugswetter Andreas SB SD" <ZeugswetterA@spardat.at>)
List pgsql-hackers
"Zeugswetter Andreas SB SD" <ZeugswetterA@spardat.at> writes:
> Yes. But I think you might have to avoid "vacuum full" during data file backup.

Why?  If vacuum is unsafe in this scenario, wouldn't it also be unsafe
in event of a system crash?

I do believe that vacuum should (but presently does not) emit a WAL
record showing its truncation of the file, so that the equivalent
truncation can be repeated during replay.  However, this is needed
in any case --- point-in-time recovery simply means replaying WAL on
a slightly longer timescale than is usual for crash-recovery.

> And you need the whole WAL including the "page images".

Check, you can't compress out the page images.
        regards, tom lane


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