From: Harald Fuchs <hf0614x@protecting.net>
To: pgsql-sql@postgresql.org
Subject: Re: Make COUNT(*) Faster?
Date: 10 Jul 2005 14:19:56 +0200
Message-ID: <puirziluoj.fsf@srv.protecting.net> (raw)
References: <9EF2931D-1097-470D-8ECB-59D00166C96F@apple.com>
<60vf3mklue.fsf@dba2.int.libertyrms.com>
<42CE89CA.2070607@noao.edu>
<758d5e7f05070808305c049aae@mail.gmail.com>
In article <758d5e7f05070808305c049aae@mail.gmail.com>,
Dawid Kuroczko <qnex42@gmail.com> writes:
> Use
> EXPLAIN SELECT * FROM yourcountedtable;
> Planner seems to track estimated statistics on-the-fly. :)
> You can even wrap EXPLAIN SELECT in a pgsql function if you
> need it.
Do you know how to do that? A function "approx_count(tablename)"
would be really handy, but
FOR row IN EXECUTE 'EXPLAIN SELECT * FROM ' || tbl LOOP
fails with the following message:
ERROR: cannot open non-SELECT query as cursor
> PS: And be aware that these are 'statistics'. And the statement that there
> are lies, big lies and statistics is sometimes true even for PostgreSQL. ;-)
Does this mean that PostgreSQL believes only in statistics it has
faked itself? ;-)
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Subject: Re: Make COUNT(*) Faster?
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