Re: sql query not using indexes

I'm curious, I know PG doesn't have support for 'full' text indexing so I'm
wondering at what point does indexing become ineffective with text type
fields?

-Mitch

----- Original Message -----
From: "Stephan Szabo" <sszabo@megazone23.bigpanda.com>
To: "User Lenzi" <lenzi@k1.com.br>
Cc: "pgsql-sql" <pgsql-sql@postgresql.org>
Sent: Wednesday, September 20, 2000 11:23 AM
Subject: Re: [SQL] sql query not using indexes


> On Wed, 20 Sep 2000, User Lenzi wrote:
>
> > if I start a query:
> >
> > explain select * from teste where login = 'xxx'
> > results:
> > Index  Scan using  teste1 on teste (cost=0.00..97.88 rows=25 )
> >
> >
> > however a query:
> > explain select * from teste where login > 'AAA'
> > results:
> > Seq Scan on teste ....
> >
> >
> > On a machine running version 6.5 both queries results index scan.
> >
> > this results that the version 6.5 is faster than version 7.0.2 on this
> > kind of
> > query.
> >
> >
> > Any explanation???
>
> Have you done a vacuum analyze on the table?  Also, what does the row
> count for the second query look like?  It's probably deciding that
> there are too many rows that will match login >'AAA' for index scan
> to be cost effective.  So, actually, also, what does
> select count(*) from teste where login>'AAA" give you on the 7.0.2 box.
>
>
>