Re: Planner incorrectly choosing seq scan over index scan - Mailing list pgsql-performance

From Meetesh Karia
Subject Re: Planner incorrectly choosing seq scan over index scan
Date
Msg-id fc5b04ca0508011630e745176@mail.gmail.com
Whole thread Raw
In response to Re: Planner incorrectly choosing seq scan over index scan  (Tobias Brox <tobias@nordicbet.com>)
List pgsql-performance
Are you referring to the statistics gathering target for ANALYZE?  Based on your email, I just tried the following and then re-ran the explain analyze but got the same "incorrect" plan:

alter table candidates617004
    alter column sourceId set statistics 1000,
    alter column targetId set statistics 1000;
analyze candidates617004;

alter table lte_user
    alter column user_id set statistics 1000;
analyze lte_user;

Thanks for your suggestion,
Meetesh

On 8/2/05, Tobias Brox <tobias@nordicbet.com> wrote:
[Meetesh Karia - Tue at 12:19:27AM +0200]
> We're using 8.0.3 and we're seeing a problem where the planner is choosing a
> seq scan and hash join over an index scan. If I set enable_hashjoin to off,
> then I get the plan I'm expecting and the query runs a lot faster. I've also
> tried lowering the random page cost (even to 1) but the planner still
> chooses to use the hash join.

Have you tried increasing the statistics collection?

--
Tobias Brox, +47-91700050
Nordicbet, IT dept

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