From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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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 |
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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
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