On Mon, Sep 12, 2011 at 10:22 AM, Shaun Thomas <sthomas@peak6.com> wrote:
> On 09/11/2011 12:02 PM, Marti Raudsepp wrote:
>
>> Which brings me to another important point: don't do lots of small
>> write transactions, SAVEPOINTs or PL/pgSQL subtransactions. Besides
>> being inefficient, they introduce a big maintenance burden.
>
> I'd like to second this. Before a notable application overhaul, we were
> handling about 300-million transactions per day (250M of that was over a
> 6-hour period). To avoid the risk of mid-day vacuum-freeze, we disabled
> autovacuum and run a nightly vacuum over the entire database. And that was
> *after* bumping autovacuum_freeze_max_age to 600-million.
>
> You do *not* want to screw with that if you don't have to, and a setting of
> 600M is about 1/3 of the reasonable boundary there. If not for the forced
> autovacuums, a database with this much traffic would be corrupt in less than
> a week. We've managed to cut that transaction traffic by 60%, and it greatly
> improved the database's overall health.
I put it to you that your hardware has problems if you have a pg db
that's corrupting from having too much vacuum activity. I've had
exactly one pg corruption problem in the past, and it was a bad SATA
hard drive on a stats server. I have four 48 core opterons running
quite hard during the day, have autovacuum on and VERY aggresively
tuned and have had zero corruption issues in over 3 years of hard
running.
