Re: planner/optimizer question - Mailing list pgsql-performance

From Jeff
Subject Re: planner/optimizer question
Date
Msg-id 69EF9EF2-9AA2-11D8-A4E1-000D9366F0C4@torgo.978.org
Whole thread Raw
In response to Re: planner/optimizer question  ("Gary Doades" <gpd@gpdnet.co.uk>)
Responses Re: planner/optimizer question  ("Gary Doades" <gpd@gpdnet.co.uk>)
List pgsql-performance
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@jefftrout.com>
http://www.jefftrout.com/
http://www.stuarthamm.net/


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