| Lists: | pgsql-sql |
|---|
| From: | "Daniel Caune" <daniel(dot)caune(at)ubisoft(dot)com> |
|---|---|
| To: | <pgsql-sql(at)postgresql(dot)org> |
| Subject: | How to force PostgreSQL using an index |
| Date: | 2006-02-15 21:58:54 |
| Message-ID: | 1E293D3FF63A3740B10AD5AAD88535D2019091DC@UBIMAIL1.ubisoft.org |
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| Lists: | pgsql-sql |
Hi,
Is there a way to force PostgreSQL using an index for a SELECT
statement? I just want to confirm that the index PostgreSQL decides to
use is better than the index I supposed PostgreSQL would use (I already
analyze the table).
Regards,
--
Daniel CAUNE
Ubisoft Online Technology
(514) 4090 2040 ext. 5418
| From: | Andrew Sullivan <ajs(at)crankycanuck(dot)ca> |
|---|---|
| To: | pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: How to force PostgreSQL using an index |
| Date: | 2006-02-15 22:06:56 |
| Message-ID: | 20060215220656.GF6562@phlogiston.dyndns.org |
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| Lists: | pgsql-sql |
On Wed, Feb 15, 2006 at 04:58:54PM -0500, Daniel Caune wrote:
> Hi,
>
>
>
> Is there a way to force PostgreSQL using an index for a SELECT
> statement? I just want to confirm that the index PostgreSQL decides to
> use is better than the index I supposed PostgreSQL would use (I already
> analyze the table).
Your best bet is to do
set enable_indexscan=false;
and then do the EXPLAIN ANALYSE for your select.
You might also find that fiddling with other settings affects the
planner's idea of what would be a good plan. The planner is
sensitive to what it thinks it knows about your environment.
A
--
Andrew Sullivan | ajs(at)crankycanuck(dot)ca
If they don't do anything, we don't need their acronym.
--Josh Hamilton, on the US FEMA