Re: pg_dump after transaction id wraparound failure

On Mon, 2006-05-15 at 13:48, Martijn van Oosterhout wrote:
> On Mon, May 15, 2006 at 11:44:01AM -0700, Michael L. Boscia wrote:
> > Hello-
> >
> > I currently have a 1.4 TB database (pg version 7.4.8) that is experiencing
> > transaction id wraparound. I plan to pg_dump the database and initdb and
> > reload. I may reload into an 8.1 database at this time.
> >
> > I am curious how to make sure that I indeed get all the data out of the
> > tables from a pg_dump. I want to ensure that there would not be anything
> > "hidden" by the transaction id wraparound failure.
>
> pg_dump obviously won't see anything that's hidden by wraparound
> failure.
>
> Vacuum will make anything that disappeared by wraparound in the last
> billion transactions reappear, so a databasewide vacuum should solve
> all your problems, no need to dump...
>
> > My current plan is selectively dump a portion of the data (most current,
> > organized in tables by date ex xxx_2006_may) and reload. I plan to vaccuum
> > each table before dumping. Please warn me if this is not enough. Any
> > assistance is greatly appreciated.
>
> I'd say do the vacuum first, dumping the data isn't really helping much
> in this case I think (although for backups it's obviously important).

This is one of those rare instances when I'd shut down the server and
take a file system backup if I could. However, at 1.4 TB, that might be
a bit difficult... :)