From: | Martin Weinberg <weinberg(at)osprey(dot)phast(dot)umass(dot)edu> |
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To: | pgsql-general(at)postgresql(dot)org |
Cc: | weinberg(at)osprey(dot)phast(dot)umass(dot)edu |
Subject: | Performing a count(*) on a large table, how to optimize |
Date: | 1999-04-15 15:06:28 |
Message-ID: | 199904151506.LAA08377@osprey.phast.umass.edu |
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Lists: | pgsql-general |
PG folks,
I have 5 Gb table (mostly numerical values) and want to be able to
count sources in a range of values, e.g.:
select count(*) from mytable where x between 1.0 and 2.0;
I have indexed on x and vacuumed.
I notice that these take about 3 minutes on my 450 Xeon Linux box.
A very complicated where clause returning data etc. takes about
the same time.
Is there a way to optimize this type of query?
Thanks!
--M
===========================================================================
Martin Weinberg Phone: (413) 545-3821
Dept. of Physics and Astronomy FAX: (413) 545-2117/0648
530 Graduate Research Tower
University of Massachusetts
Amherst, MA 01003-4525
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