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Re: enable_joinremoval

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: enable_joinremoval
Date: 2010-03-29 14:36:14
Message-ID: 12679.1269873374@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Mon, Mar 29, 2010 at 4:33 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> So I think we need a parameter for join removal also.

> I had this in my original patch but Tom wanted it taken out.

And I still don't want it.  We are NOT going in the direction of adding
an enable_ knob for every single planner activity --- do you have the
faintest idea how many there would be?  We have such knobs for a small
number of cases where it's arguable that the action might be the wrong
thing for a particular query.  Join removal, if applicable, can't
possibly be the wrong choice; it's better than every other join strategy.

			regards, tom lane

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