Re: difficulties with time based queries

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Rainer Mager" <rainer(at)vanten(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: difficulties with time based queries
Date: 2009-04-06 01:33:17
Message-ID: 7371.1238981597@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

"Rainer Mager" <rainer(at)vanten(dot)com> writes:
>> From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
>> Hmm ... it's pretty unusual to see the index fetch portion of a bitmap
>> scan take the bulk of the runtime. Usually that part is fast and where
>> the pain comes is in fetching from the heap. I wonder whether that
>> index has become bloated. How big are the table and the index
>> physically? (Look at pg_class.relpages, or if you want a really
>> accurate number try pg_relation_size().)

> Can you give me some more info on how to look at these stats?

Since you've got 8.3 it's easy: select pg_relation_size('tablename')
(or indexname). The result is in bytes, so you might want to
divide by 1K or 1M to keep the number readable.

regards, tom lane

In response to

Responses

Browse pgsql-performance by date

  From Date Subject
Next Message Greg Sabino Mullane 2009-04-06 02:11:21 Re: Best replication solution?
Previous Message Rainer Mager 2009-04-06 01:26:08 Re: difficulties with time based queries