| From: | Brent Wood <b(dot)wood(at)niwa(dot)co(dot)nz> |
|---|---|
| To: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Can this be indexed? |
| Date: | 2004-11-07 20:30:17 |
| Message-ID: | 20041108092555.M64803@storm-user.niwa.co.nz |
| Views: | Whole Thread | Raw Message | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
>
> >Net Virtual Mailing Lists wrote:
> >> Is there a way to create an index that would make this query be efficient
> >> and not perform a sequential scan?
> >>
> >> SELECT count(*) AS count,id FROM sometable GROUP BY id;
> >
> >Indexes cannot be used for retrieving results...
I'm not sure if it would improve performance at all, given the entire
table needs to be scanned anyway, but add a where clause "where id > 0"
should allow an index on id to be used.
Possibly a bit like speeding up "select max(id) from ..."
Someone who knows more about the internals of Postgis can prob comment on
the validity/idiocy of this suggestion :-)
Brent Wood
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Gary L. Burnore | 2004-11-07 20:37:44 | Re: RFD: comp.databases.postgresql.general |
| Previous Message | Greg Stark | 2004-11-07 20:16:58 | Re: SQL question |