From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
Cc: | Anj Adu <fotographs(at)gmail(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: slow index lookup |
Date: | 2010-06-23 02:01:53 |
Message-ID: | 11812.1277258513@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Excerpts from Anj Adu's message of mar jun 22 17:44:39 -0400 2010:
>> This query seems unreasonable slow on a well-indexed table (13 million
>> rows). Separate indexes are present on guardid_id , from_num and
>> targetprt columns.
> Maybe you need to vacuum or reindex?
Rethinking the set of indexes is probably a more appropriate suggestion.
Separate indexes aren't usefully combinable for a case like this --- in
principle the thing could do a BitmapAnd, but the startup time would be
pretty horrid, and the LIMIT 1 is discouraging it from trying that.
If this is an important case to optimize then you need a 3-column index.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Anj Adu | 2010-06-23 03:05:20 | Re: slow index lookup |
Previous Message | Anj Adu | 2010-06-23 01:21:46 | Re: slow index lookup |