Re: XID wraparound in 8.4

Anj Adu <fotographs(at)gmail(dot)com> writes:
> Assuming that autovacuum is off in 8,2 and upwards versions, would I
> still have to do a database-wide vacuumdb OR would vacuuming
> individual tables that are permanent be sufficient to take care of XID
> wraparound?

In recent releases it is not possible to turn off autovacuum to the
extent of preventing it from doing anti-wraparound vacuuming, so your
question is a bit mis-posed. But yes, you do need a database-wide
manual vacuum if you are trying to forestall automatic anti-wraparound
vacuuming. Vacuuming individual tables isn't sufficient unless you get
*every single one*, including the system catalogs.

In practice, I think worrying about this is pointless in modern PG.
If you want control over the timing of vacuuming on individual large
tables, do them when you want to. The system will occasionally force
vacuums on small tables to prevent wraparound, but that isn't going
to cause you any performance problems.

regards, tom lane