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Re: generalizing the planner knobs

From: Rod Taylor <pg(at)rbt(dot)ca>
To: Greg Stark <gsstark(at)mit(dot)edu>
Cc: "Pollard, Mike" <mpollard(at)cincom(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>, Neil Conway <neilc(at)samurai(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: generalizing the planner knobs
Date: 2005-12-02 15:20:07
Message-ID: 1133536807.12218.168.camel@home (view raw or flat)
Thread:
Lists: pgsql-hackers 
> In the extreme, no amount of added intelligence in the optimizer is going to
> help it come up with any sane selectivity estimate for something like 
> 
>   WHERE radius_authenticate(user) = 'OK'

Why not?

The missing capability in this case is to be able to provide or generate
(self learning?) statistics for a function that describe a typical
result and the cost of getting that result.
--

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