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Re: hashjoin chosen over 1000x faster plan

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: hashjoin chosen over 1000x faster plan
Date: 2007-10-10 06:31:44
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Tue, 2007-10-09 at 15:09 -0500, Kevin Grittner wrote:

> I have a situation where a query is running much slower than I would
> expect.  The ANALYZE showed that it is hashing some information which
> is rarely needed.  When I set enable_hashjoin = off for the
> connection the query run in 1/1000 the time.

Can you confirm the two queries give identical outputs? It isn't clear
to me why the second sort is (never executed) in your second plan, which
I would only expect to see for an inner merge join.

Can you show the details for ControlRecord also.

  Simon Riggs

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