On Tue, 26 Jun 2001, Alex Knight wrote:
> On Tue, 26 Jun 2001, Philip Molter wrote:
>
> > I have a Postgres application running right now. The thing is
> > constantly doing 3-5 updates/sec and 1-2 multi-join selects/sec and
> > performance is actually doing all right. Unfortunately, as the system
> > runs, performance degrades, which I guess has been documented, although
> > I still don't understand why.
> >
> > To work around this, I have a cron job that runs every hour and vacuum
> > analyzes the three tables that are actually updated significantly. Most of the time, it works fine, but recently,
I'vebeen getting this error:
> >
> > NOTICE: Child itemid in update-chain marked as unused - can't continue
> > repair_frag
> >
> > What causes this and how do I make it stop? When this happens,
> > whatever table is affected doesn't get analyzed and the database
> > continues its downward resource spiral.
>
> I'm fairly sure you are _suppose_ to run VACUUM ANALYZE when there are no
> clients connected to the database. You may have to have your cron job
> temporarily suspend remote connectivity while the actions are performed.
This is definitely FALSE. Vacuum does not lock the database, it acquires
certain locks while its vacuuming certain tables. I.E. your clients may
not be able to modify table while its being vacuumed.
Regarding the error you are getting: Which postgres version is it? See if
7.1.2 has it fixed...
