Re: Optimization rules for semi and anti joins

From: Dimitri Fontaine <dfontaine(at)hi-media(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: Optimization rules for semi and anti joins
Date: 2009-02-10 20:41:46
Message-ID: FAEBF2D0-40DA-434D-92D2-3DDB33F8B357@hi-media.com
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Hi,

Le 10 févr. 09 à 21:10, Tom Lane a écrit :

> I wrote (in response to Kevin Grittner's recent issues):
>> Reflecting on this further, I suspect there are also some bugs in the
>> planner's rules about when semi/antijoins can commute with other
>> joins;
>
> After doing some math I've concluded this is in fact the case. Anyone
> want to check my work?

I don't know how easy it would be to do, but maybe the Coq formal
proof management system could help us here:
http://coq.inria.fr/

The harder part in using coq might well be to specify the problem the
way you just did, so...

HTH,
--
dim

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