| 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 |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| 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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