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Re: optimizing selects on time-series data in Pg

From: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>
To: Aditya <aditya(at)grot(dot)org>
Cc: <sfpug(at)postgresql(dot)org>
Subject: Re: optimizing selects on time-series data in Pg
Date: 2003-08-01 18:28:05
Message-ID: 20030801112639.U56675-100000@megazone.bigpanda.com (view raw or flat)
Thread:
Lists: sfpug
On Fri, 1 Aug 2003, Aditya wrote:

> On Fri, Aug 01, 2003 at 11:07:41AM -0700, Stephan Szabo wrote:
> > > - forced the planner not to use sequential scan and verified that the index
> > > scan was in fact more costly then, here's a somewhat edited transcript (only
> > > for brevity):
> >
> > Hmm, does a two column index on timestamp,virtualhost (or possibly the
> > other way around) help at all when forcing an index scan?  I wouldn't
> > guess that it'd help enough, but it might be worth trying.
>
> hm, didn't make a difference (I deleted a bunch of rows this morning to see
> what I could get away with, hence the difference in the total row count):

Does it lower the realtime after a set enable_seqscan=off; (also an
explain analyze would let us see if there's a type difference that causes
it to not want to use the index for the date comparison).


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