Re: Point in Time Recovery - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Point in Time Recovery
Date
Msg-id 24226.1091207086@sss.pgh.pa.us
Whole thread Raw
In response to Re: Point in Time Recovery  ("Zeugswetter Andreas SB SD" <ZeugswetterA@spardat.at>)
Responses Re: Point in Time Recovery  (Mark Kirkwood <markir@coretech.co.nz>)
List pgsql-hackers
"Zeugswetter Andreas SB SD" <ZeugswetterA@spardat.at> writes:
> If you use a readable file you will also need a feature for restore
> (or a tool) to create an appropriate pg_control file, or are you
> intending to still require that pg_control be the first file backed
> up.

No, the entire point of this exercise is to get rid of that assumption.
You do need *a* copy of pg_control, but the only reason you'd need to
back it up first rather than later is so that its checkpoint pointer
points to the last checkpoint before the dump starts.  Which is the
information we want to put in the archive-label file insted.

If a copy of pg_control were sufficient then I'd be all for using it as
the archive-label file, but it's *not* sufficient because you also need
the ending WAL offset.  So we need a different file layout in any case,
and we may as well take some pity on the poor DBA and make the file
easily human-readable.
        regards, tom lane


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