Re: How does Index Scan get used

On Fri, 22 Feb 2002, Samuel J. Sutjiono wrote:

[Please answer below cited parts.]

> No, I didn't.
>
> ----- Original Message -----
> From: "Holger Marzen" <holger@marzen.de>
> To: "Samuel J. Sutjiono" <ssutjiono@wc-group.com>
> Cc: <pgsql-general@postgresql.org>
> Sent: Friday, February 22, 2002 10:25 AM
> Subject: Re: [GENERAL] How does Index Scan get used
>
>
> > On Fri, 22 Feb 2002, Samuel J. Sutjiono wrote:
> >
> > > I tried an Index Scan but I kept on getting Seq Scan. Do you know why ?
> What do I need to do to get my query to use index scan (I tried to turn it
> on  by doing SET ENABLE_indexscan = on; but it didn't work)
> > >
> > > explain select * from test where test_col like 'abc/%';
> > >
> > > NOTICE:  QUERY PLAN:
> > >
> > > Seq Scan on test  (cost=0.00..22.50 rows=10 width=12)
> >
> > Did you do a vacuum analyze after creating the index?

If you don't do a "vacuum analyze" for a table after creating an index
then Postgres has not all the informations to optimize a query. "vaccum
analyze" is recommended on a regular basis. I do it every night.

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