From: Jay Levitt <jay.levitt@gmail.com>
To: pgsql-performance@postgresql.org
Subject: Cost estimate vs. actual - do I care?
Date: Sun, 01 Jan 2012 13:59:25 -0500
Message-ID: <4F00AD0D.6000501@gmail.com> (raw)
I gather that a big part of making queries performant is making sure the
planner's estimates reflect reality.
Given a random explain analyze line:
Limit (cost=0.02..943.11 rows=50 width=16) (actual time=0.603..79.729
rows=50 loops=1)
which is the truer statement?
1. As long as costs go up with actual time, you're fine.
2. You should try to ensure that costs go up linearly with actual time.
3. You should try to ensure that costs are as close as possible to actual time.
4. The number "4".
Jay Levitt
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Subject: Re: Cost estimate vs. actual - do I care?
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