count() in 9.2

From: Steve Horn <steve(at)stevehorn(dot)cc>
To: pgsql-novice(at)postgresql(dot)org
Subject: count() in 9.2
Date: 2012-10-17 15:00:39
Message-ID: CAFLkBaVjm9sF38ew_3quhKb7DRn_b5fBghJmgmda=rbB5jYW1Q@mail.gmail.com
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One of the reasons that my team could not take advantage of PostgreSQL was
due to the poor performance of count(*) aggregate function.

I visited the "Slow Counting" page on the wiki (
http://wiki.postgresql.org/wiki/Slow_Counting) and it states:
*"Note that the following article only applies to versions of PostgreSQL
prior to 9.2. Index-only scans are now implemented."*
*
*
So does this mean that count() is no longer slow? If not, how much faster
is it? And what does it mean when it says "Index-only scans are now
implemented."?

Thanks for your help!

--
Steve Horn

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