Re: Mirroring databases in v8 - Mailing list pgsql-general

From Tom Lane
Subject Re: Mirroring databases in v8
Date
Msg-id 25460.1097071576@sss.pgh.pa.us
Whole thread Raw
In response to Re: Mirroring databases in v8  (Glen Eustace <geustace@godzone.net.nz>)
Responses Re: Mirroring databases in v8
List pgsql-general
Glen Eustace <geustace@godzone.net.nz> writes:
> Having read this, it would seem I might be jumping the gun a bit.  The
> method given could be used to copy a running database to another system
> but I'm not sure how it would work if the mirrored database is required
> to be online at the same time.

It wouldn't.  You can have a "hot spare" database via log shipping, but
there is zero chance of allowing the backup to run any independent
transactions.  (If it did, its xact counter and pg_clog would get out of
sync with the master, causing all subsequently copied data to be
invalid.  AFAICS, even read-only transactions would be problematic.)

Not sure if you are familiar with the Slony project, but that is
probably your best bet for data propagation to a live slave at present.

            regards, tom lane

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