Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)

From: Mischa
Subject: Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)
Date: ,
Msg-id: 1112909198.4255a58eae0d8@webmail.telus.net
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In response to: Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Tom Lane)
Responses: Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Tom Lane)
List: pgsql-performance

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Plan for relatively simple query seems to be very inefficient  (Arjen van der Meijden, )
 Re: Plan for relatively simple query seems to be very inefficient  (Steve Atkins, )
  Re: Plan for relatively simple query seems to be very inefficient  (Arjen van der Meijden, )
 Re: Plan for relatively simple query seems to be very inefficient  (Tom Lane, )
  Re: Plan for relatively simple query seems to be very inefficient  (Arjen van der Meijden, )
   Re: Plan for relatively simple query seems to be very inefficient  (Tom Lane, )
    Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Tom Lane, )
     Re: [HACKERS] Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  ("Jim C. Nasby", )
      Re: [HACKERS] Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Tom Lane, )
       Re: [HACKERS] Recognizing range constraints (was Re: Plan  (John A Meinel, )
        Re: [HACKERS] Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Tom Lane, )
       Re: [HACKERS] Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  ("Jim C. Nasby", )
     Re: Recognizing range constraints (was Re: Plan for  (Simon Riggs, )
     Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Bruno Wolff III, )
      Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Tom Lane, )
       Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Mischa, )
        Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (Tom Lane, )
         Re: Recognizing range constraints (was Re: Plan for relatively simple query seems to be very inefficient)  (, )
 Re: Plan for relatively simple query seems to be very inefficient  ("Dave Held", )
  Re: Plan for relatively simple query seems to be very inefficient  (Tom Lane, )
  Re: Plan for relatively simple query seems to be very inefficient  (Tom Lane, )
 Re: Plan for relatively simple query seems to be very inefficient  (Mischa, )

Quoting Tom Lane <>:

> Yeah, the whole thing is only a heuristic anyway.  I've been coming
> around to the view that relation membership shouldn't matter, because
> of cases like
>
>     WHERE a.x > b.y AND a.x < 42
>
> which surely should be taken as a range constraint.

Out of curiosity, will the planner induce "b.y < 42" out of this?

--
"Dreams come true, not free."



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