From: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
---|---|
To: | Ben-Nes Yonatan <da(at)canaan(dot)co(dot)il> |
Cc: | Sean Davis <sdavis2(at)mail(dot)nih(dot)gov>, Dann Corbit <DCorbit(at)connx(dot)com>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Query results caching? |
Date: | 2005-08-22 22:38:58 |
Message-ID: | 20050822223857.GP72767@pervasive.com |
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Lists: | pgsql-general |
On Tue, Aug 23, 2005 at 12:27:39AM +0200, Ben-Nes Yonatan wrote:
> Jim C. Nasby wrote:
> >Emptying the cache will not show real-life results. You are always going
> >to have some stuff cached, even if you get a query for something new. In
> >this case (since you'll obviously want those indexes there), after some
> >amount of time you will have most (if not all) of the non-leaf index
> >pages cached, since they take a fairly small amount of memory and are
> >frequently accessed. This makes index traversal *much* faster than your
> >initial case shows, even if you query on something different each time.
> >Testing with a completely empty cache just isn't that realistic.
>
> As far as I understand it at my situation where all of the data is
> deleted and inserted each day from the start (INDEX will get lost with
> it..) & the endless variety of possible keywords search's & the immense
> size of the tables, the following reason wont last.. or am I wrong here?
You're wrong - to an extent. Remember that while you're loading all that
data it's also being cached. Now, some of it will probably end up
falling out of the cache as all the data is read in, but you certainly
won't be starting from the clean slate that you're looking for.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com 512-569-9461
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