Re: Minimally avoiding Transaction Wraparound in VLDBs

On Thu, Sep 01, 2005 at 04:21:58AM -0000, Andrew - Supernews wrote:
> On 2005-09-01, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> > On Thu, Sep 01, 2005 at 01:57:02AM +0100, Simon Riggs wrote:
> >
> >> > If you're using autovacuum then the problem is already taken care of.
> >> 
> >> autovacuum will respond only to UPDATEs and DELETEs. In the scenario I
> >> outline, these will *never* occur on the largest tables. A VACUUM would
> >> still eventually be required to freeze long lived tuples and this would
> >> not be performed by autovacuum.
> >
> > Hum, I don't understand -- if you don't want to vacuum the table, why
> > run vacuum at all?  You can (as of 8.1) disable autovacuum for specific
> > tables.  The exception is that you are forced to run a database-wide
> > VACUUM once in a while (every billion-and-so), but this will hopefully
> > disappear in 8.2 too,
> 
> Wishful thinking, or do you have a concrete plan to achieve it?

We talked about it during the autovacuum discussions just before feature
freeze.  There is a vague plan which I intend to study eventually.

-- 
Alvaro Herrera -- Valdivia, Chile         Architect, www.EnterpriseDB.com
"On the other flipper, one wrong move and we're Fatal Exceptions"
(T.U.X.: Term Unit X  - http://www.thelinuxreview.com/TUX/)