Re: Help: how to speed up query after db server reboot

Magnus Hagander <magnus@hagander.net> writes:
> On Wed, Sep 2, 2009 at 00:01, Wei Yan<weiyan1@gmail.com> wrote:
>> Looks like after postgres db server reboot, first query is very slow
>> (10+mins). After the system cache built, query is pretty fast.
>> Now the question is how to speed up the first query slow issue?

> Schedule a run of a couple of representative queries right as the
> database has started? That should pre-populate the cache before your
> users get there, hopefully.

I wonder if VACUUMing his key tables would be a good answer.  I bet that
a lot of the problem is swapping in indexes in a slow random-access
fashion.  In recent-model Postgres, VACUUM will do a sequential scan of
the indexes (at least for btree) which should be a much more efficient
way of bringing them into kernel cache.

            regards, tom lane