| From: | Francisco Olarte <folarte(at)peoplecall(dot)com> |
|---|---|
| To: | Kaijiang Chen <chenkaijiang(at)gmail(dot)com> |
| Cc: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Pg Bugs <pgsql-bugs(at)postgresql(dot)org> |
| Subject: | Re: BUG #14302: SQL with LIMIT degrades performance seriously |
| Date: | 2016-08-31 13:58:58 |
| Message-ID: | CA+bJJbx3o_tPQpzbkYqzgMhi0jL53OF0YfpB6iszNOpfd8FhAA@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-bugs |
Top posting makes the flow difficult to follow, editing a little bit.
>> Why not just create the correct index on each partition?
>> (parent_id,user_id)
On Wed, Aug 31, 2016 at 2:42 PM, Kaijiang Chen <chenkaijiang(at)gmail(dot)com> wrote:
> It couldn't solve the problem.
> I've already created 2 btree indexes, one for parent_id, the other for
> user_id.
A (parent_id, user_id) index can be used instead of the one for
parent_id, so it will nbot need to much extra, and can solve some
queries. The planner can normally detected where some keys can be
solved directly with a composite index.
> Do you mean to create an multi-column index on (parent_id, user_id)? --
> still couldn't solve the problem, since we still need index for user_id (for
> other sql) and planner will turn to user_id index.
How do you know it will turn to the bad index?
Francisco Olarte.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Christoph Berg | 2016-08-31 15:37:37 | Re: BUG #14294: Problem in generate series between dates |
| Previous Message | Francisco Olarte | 2016-08-31 13:55:30 | Re: BUG #14302: SQL with LIMIT degrades performance seriously |