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Re: Full text indexing preformance! (long)

From: "Mitch Vincent" <mitch(at)venux(dot)net>
To: <pgsql-hackers(at)postgresql(dot)org>
Cc: <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: Full text indexing preformance! (long)
Date: 2000-05-31 01:53:01
Message-ID: 003801bfcaa2$fb8d08e0$0300000a@doot.org (view raw or flat)
Thread:
Lists: pgsql-hackers
> > Well, of course the whole *point* of LIMIT is that it stops short of
> > scanning the whole query result.  So I'm afraid you're kind of stuck
> > as far as the performance goes: you can't get a count() answer without
> > scanning the whole query.

Right, that's what I thought.

> > I'm a little curious though: what is the typical count() result from
> > your queries?  The EXPLAIN outputs you show indicate that the planner
> > is only expecting about one row out now, but I have no idea how close
> > that is to the mark.  If it were really right, then there'd be no
> > difference in the performance of LIMIT and full queries, so I guess
> > it's not right; but how far off is it?

Well, count does always return 1 row, though what's in that one row is as
varying as 0 to the number of records in the applicants database (about
11,000)..

Anyway, I thank you and appreciate your input..

-Mitch




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