Re: Optimizing Query

Did you run VACUUM ANALYZE after running CLUSTER?

Michael Fork - CCNA - MCP - A+
Network Support - Toledo Internet Access - Toledo Ohio

On Mon, 5 Mar 2001, Justin Long wrote:

> Ok, now I have another question... it doesn't seem to be accessing the index.
>
> explain select k.kbid,k.title from knowledge k , kbwords w0 , kbwords w1
> WHERE ((k.kbid=w0.kbid and w0.wordid=42743) AND (k.kbid=w1.kbid and
> w1.wordid=85369))
>
> NOTICE: QUERY PLAN:
>
> Merge Join (cost=32339.30..35496.97 rows=19262538 width=24)
> -> Merge Join (cost=16530.24..16668.77 rows=233274 width=20)
> -> Sort (cost=15809.06..15809.06 rows=8257 width=4)
> -> Seq Scan on kbwords w1 (cost=0.00..15271.85 rows=8257
> width=4)
> -> Sort (cost=721.18..721.18 rows=2825 width=16)
> -> Seq Scan on knowledge k (cost=0.00..559.25 rows=2825
> width=16)
> -> Sort (cost=15809.06..15809.06 rows=8257 width=4)
> -> Seq Scan on kbwords w0 (cost=0.00..15271.85 rows=8257 width=4)
>
> Note the sequential scans... there is a wordindex where w0.wordid=42743...
> why isn't it doing an indexscan? wouldn't that be more efficient?
>
> Justin
>
>
> At 04:45 PM 3/5/2001 -0500, you wrote:
> >Yes.
> >
> > > On Mon, Mar 05, 2001 at 04:07:57PM -0500, Bruce Momjian allegedly wrote:
> > > > Have you tried VACUUM ANALYZE and CLUSTER?
> > >
> > > I assume CLUSTER still drops all indexes except the one you're clustering
> > > on?
> > >
> > > Mathijs
> > > --
> > > It's not that perl programmers are idiots, it's that the language
> > > rewards idiotic behavior in a way that no other language or tool has
> > > ever done.
> > > Erik Naggum
> > >
> >
> >
> >--
> > Bruce Momjian | http://candle.pha.pa.us
> > pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
> > + If your life is a hard drive, | 830 Blythe Avenue
> > + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
>
>
> ____________________________________________________________________
> Justin Long Network for Strategic Missions
> justinlong(at)strategicnetwork(dot)org 1732 South Park Court
> http://www.strategicnetwork.org Chesapeake, VA 23320, USA
> Reality Check e-zine: reality-check-subscribe(at)yahoogroups(dot)com
> ____________________________________________________________________
> Law: Never retreat. Never surrender. Never cut a deal with a dragon.
> Corollary: No armor? Unclean life? Then do not mess in the affairs
> of dragons, for you are crunchy and taste good with ketchup.
>