count(*) slow on large tables - Mailing list pgsql-performance

From Dror Matalon
Subject count(*) slow on large tables
Date
Msg-id 20031002191547.GZ87525@rlx11.zapatec.com
Whole thread Raw
Responses Re: count(*) slow on large tables
Re: count(*) slow on large tables
List pgsql-performance
Hi,

I have a somewhat large table, 3 million rows, 1 Gig on disk,  and growing. Doing a
count(*) takes around 40 seconds.

Looks like the count(*) fetches the table from disk and goes through it.
Made me wonder, why the optimizer doesn't just choose the smallest index
which in my case is around 60 Megs and goes through it, which it could
do in a fraction of the time.

Dror


--
Dror Matalon
Zapatec Inc
1700 MLK Way
Berkeley, CA 94709
http://www.zapatec.com

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