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Re: Improving NOT IN

From: "Simon Riggs" <simon(at)2ndquadrant(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Improving NOT IN
Date: 2007-01-30 23:24:40
Message-ID: 1170199480.3681.319.camel@silverbirch.site (view raw or flat)
Thread:
Lists: pgsql-hackers
On Tue, 2007-01-30 at 18:06 -0500, Tom Lane wrote:
> "Simon Riggs" <simon(at)2ndquadrant(dot)com> writes:
> > What would be wrong with checking for a NOT NULL constraint? Thats how
> > other planners cope with it. Or are you thinking about lack of plan
> > invalidation?
> 
> Yup, without that, depending on constraints for plan correctness is
> pretty risky.
> 
> Basically what I see here is a whole lot of work and new executor
> infrastructure for something that will be a win in a very narrow
> use-case and a significant loss the rest of the time.  I think there
> are more productive ways to spend our development effort.

For that part of the email, I was talking about your ideas on NOT IN.

Checking for the explicit exclusion of NULLs is worthwhile with/without
plan invalidation.

-- 
  Simon Riggs             
  EnterpriseDB   http://www.enterprisedb.com



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