| From: | Anj Adu <fotographs(at)gmail(dot)com> |
|---|---|
| To: | Matthew Wakeling <matthew(at)flymine(dot)org> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: slow query |
| Date: | 2010-06-04 17:25:30 |
| Message-ID: | AANLkTikqPktNEIFMB6lNm7vjYVxtatWNSBJlGC3N_WTb@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
I'm interested in why the two partitions dev4_act_dy_fact and
> dev4_act_dy_fact_2010_05_t3 are treated so differently. I'm guessing that
> the former is the parent and the latter the child table?
Yes..you are correct.
>
> When accessing the parent table, Postgres is able to use a bitmap AND index
> scan, because it has the two indexes dev4_act_dy_dm_nd_indx and
> dev4_act_dy_dm_cd_indx. Do the child tables have a similar index setup?
Yes..the child table have indexes on those fields as well
>
> Incidentally, you could get even better than a bitmap AND index scan by
> creating an index on (node_id, thedate) on each table.
Will this perform better than separate indexes ?
>
>> random_page_cost=1
>
> I agree with Tomas that this is rarely a useful setting.
>
> Matthew
>
> --
> You can configure Windows, but don't ask me how. -- Bill Gates
>
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