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From: Antonin Houska <ah@cybertec.at>
To: pgsql-hackers@postgresql.org
Subject: Re: Performance improvement for joins where outer side is unique
Date: Wed, 25 Jan 2017 16:56:21 +0100
Message-ID: <28690.1485359781@localhost> (raw)
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David Rowley <david.rowley@2ndquadrant.com> wrote:
> On 19 January 2017 at 11:06, David Rowley <david.rowley@2ndquadrant.com> wrote:
> > Old patch no longer applies, so I've attached a rebased patch. This
> > also re-adds a comment line which I mistakenly removed.
> 
> (meanwhile Andres commits 69f4b9c)
> 
> I should've waited a bit longer.
> 
> Here's another that fixes the new conflicts.

I suspect that "inner" and "outer" relation / tuple are sometimes confused in
comments:


* analyzejoins.c:70

 "searches for subsequent matching outer tuples."


* analyzejoins.c:972

/*
 * innerrel_is_unique
 *	  Check for proofs which prove that 'innerrel' can, at most, match a
 *	  single tuple in 'outerrel' based on the join condition in
 *	  'restrictlist'.
 */


* relation.h:1831

	bool		inner_unique;	/* inner side of join matches no more than one
								 * outer side tuple */


-- 
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at


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