From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <david.rowley@2ndquadrant.com>
cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>,
        Simon Riggs <simon@2ndquadrant.com>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Performance improvement for joins where outer side is unique
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Comments: In-reply-to David Rowley <david.rowley@2ndquadrant.com>
	message dated "Mon, 14 Mar 2016 01:06:33 +1300"
Date: Fri, 01 Apr 2016 12:52:42 -0400
Message-ID: <30364.1459529562@sss.pgh.pa.us>
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David Rowley <david.rowley@2ndquadrant.com> writes:
> On 12 March 2016 at 11:43, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> It seems like the major intellectual complexity here is to figure out
>> how to detect inner-side-unique at reasonable cost.  I see that for
>> LEFT joins you're caching that in the SpecialJoinInfos, which is probably
>> fine.  But for INNER joins it looks like you're just doing it over again
>> for every candidate join, and that seems mighty expensive.

> I have a rough idea for this, but I need to think of it a bit more to
> make sure it's bulletproof.

Where are we on this?  I had left it alone for awhile because I supposed
that you were going to post a new patch, but it's been a couple weeks...

			regards, tom lane


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