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Message-ID: <4F00AD0D.6000501@gmail.com>
Date: Sun, 01 Jan 2012 13:59:25 -0500
From: Jay Levitt <jay.levitt@gmail.com>
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Subject: Cost estimate vs. actual - do I care?
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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