Doug McNaught wrote:
> Ben Clewett <B.Clewett@roadrunner.uk.com> writes:
>
>
> > > So does PostgreSQL (pg_dump/pg_dumpall).
> >
> > I have used this, and it's a great command.
> >
> > I could not work out from the documentation whether it takes a
> > snapshot at the start time, or archives data at the time it find's it.
> > The documentation (app-pg-dump.html). As the documentation does not
> > clarify this very important point, I desided it's not safe to use when
> > the system is in use.
>
> Ummm, quoting from the pg_dump manpage:
>
> pg_dump makes consistent backups even if the database is
> being used concurrently. pg_dump does not block other
> users accessing the database (readers or writers).
>
> What part of this isn't clear?
>
> It's safe. pg_dump does all its work inside a transaction, so MVCC
> rules automatically guarantee that it sees a consistent snapshot.
Too many people have missed that point --- it was too far down in the
manual page, after a long discussion about output formats. Now it is
right in the first paragraph, which should eliminate that question ---
it was almost becoming an FAQ.
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
359-1001+ If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square,
Pennsylvania19073
