Re: Optimizing NOT IN plans / verify rewrite

From: Maciek Sakrejda <msakrejda(at)truviso(dot)com>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Optimizing NOT IN plans / verify rewrite
Date: 2010-08-02 19:42:43
Message-ID: AANLkTin=-ZKfcZwSdWv03SzMeKGszHq=87k-hwHM3BRq@mail.gmail.com
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> Can "b" be null in any of these tables? If not, then you can
> rewrite your query to us NOT EXISTS and have the same semantics.
> That will often be much faster.

Thanks, Kevin.

No NULLs. It looks like it's a good deal slower than the LOJ version,
but a good deal faster than the original. Since the equivalence of
semantics is much easier to verify here, we may go with this (at least
for the moment).
---
Maciek Sakrejda | System Architect | Truviso

1065 E. Hillsdale Blvd., Suite 230
Foster City, CA 94404
(650) 242-3500 Main
www.truviso.com

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