Re: difficulties with time based queries - Mailing list pgsql-performance

From Tom Lane
Subject Re: difficulties with time based queries
Date
Msg-id 7371.1238981597@sss.pgh.pa.us
Whole thread Raw
In response to Re: difficulties with time based queries  ("Rainer Mager" <rainer@vanten.com>)
Responses Re: difficulties with time based queries  ("Rainer Mager" <rainer@vanten.com>)
List pgsql-performance
"Rainer Mager" <rainer@vanten.com> writes:
>> From: Tom Lane [mailto:tgl@sss.pgh.pa.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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