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enable_joinremoval

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: enable_joinremoval
Date: 2010-03-29 08:33:50
Message-ID: 1269851630.3684.3636.camel@ebony (view raw or flat)
Thread:
Lists: pgsql-hackers
We have planner method parameters for many important parts of the
planner. We don't have any parameter for join removal, AFAIK.

The first question I get asked is "can I see the tables it removed?".
This has been asked of me 3 times now this year, always first question.
Same issue applies to constraint exclusion.

But we *can* do this with constraint_exclusion, simply by turning it off
and checking the two outputs.

So I think we need a parameter for join removal also.

I don't want to turn it off, but I think we need a way for people to
check themselves that the removal of the joins is not an error. I
foresee many false bug reports along the lines of "optimizer ate my join
and I want it back". 

-- 
 Simon Riggs           www.2ndQuadrant.com


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Next:From: Stefan KaltenbrunnerDate: 2010-03-29 08:42:39
Subject: Re: Alpha release this week?
Previous:From: Pavel StehuleDate: 2010-03-29 08:33:07
Subject: Re: join removal

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