Re: planner/optimizer question

From: Jeff <threshar(at)torgo(dot)978(dot)org>
To: "Gary Doades" <gpd(at)gpdnet(dot)co(dot)uk>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: planner/optimizer question
Date: 2004-04-30 12:32:16
Message-ID: 69EF9EF2-9AA2-11D8-A4E1-000D9366F0C4@torgo.978.org
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On Apr 30, 2004, at 3:01 AM, Gary Doades wrote:

[ pg query plan, etc ]

I wonder if other parts of the plan are affecting the speed.

I've recently run into a case where a merge join plan was chosen for
this query, which took 11 seconds to execute. Forcing it to pick a
nested loop join dropped it to 3. (Updating my
default_statistics_target to 500 caused the planner to choose nested
loop join)

So, is the plan really the same?

A better comparision query may be a simple "select a from mytable
where a between foo and bar" to get an index scan. In that case its a
straight up, vanilla index scan. Nothing else getting in the way.

--
Jeff Trout <jeff(at)jefftrout(dot)com>
http://www.jefftrout.com/
http://www.stuarthamm.net/

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