От: Csaba Nagy
Тема: Re: Hints proposal
Дата: ,
Msg-id: 1161005266.28751.145.camel@coppola.muc.ecircle.de
(см: обсуждение, исходный текст)
Ответ на: Re: Hints proposal  (Mark Kirkwood)
Ответы: Re: Hints proposal  (Brian Hurt)
Re: Hints proposal  (Mark Kirkwood)
Список: pgsql-performance

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Hints proposal  ("Jim C. Nasby", )
 Re: Hints proposal  (Bruce Momjian, )
  Re: Hints proposal  (Heikki Linnakangas, )
   Re: Hints proposal  (Tom Lane, )
   Re: Hints proposal  ("Jim C. Nasby", )
 Re: Hints proposal  ("Joshua Marsh", )
  Re: Hints proposal  ("Bucky Jordan", )
   Re: Hints proposal  (Robert Treat, )
    Re: Hints proposal  (Tom Lane, )
     Re: Hints proposal  (Robert Treat, )
  Re: Hints proposal  ("Jim C. Nasby", )
 Re: Hints proposal  (Tom Lane, )
  Re: Hints proposal  ("Merlin Moncure", )
  Re: [HACKERS] Hints proposal  ("Jim C. Nasby", )
   Re: [HACKERS] Hints proposal  (Josh Berkus, )
    Re: [HACKERS] Hints proposal  ("Jim C. Nasby", )
     Re: [HACKERS] Hints proposal  (Josh Berkus, )
      Re: [HACKERS] Hints proposal  ("Bucky Jordan", )
       Re: [HACKERS] Hints proposal  (Alvaro Herrera, )
      Re: [HACKERS] Hints proposal  ("Jim C. Nasby", )
       Re: [HACKERS] Hints proposal  (Tom Lane, )
       Re: [HACKERS] Hints proposal  ("Bucky Jordan", )
        Re: Hints proposal  ("Craig A. James", )
         Re: Hints proposal  (, )
         Re: Hints proposal  (Mark Kirkwood, )
          Re: Hints proposal  (Csaba Nagy, )
           Re: Hints proposal  (Brian Hurt, )
            Re: Hints proposal  (Bruce Momjian, )
            Re: Hints proposal  (Shaun Thomas, )
           Re: Hints proposal  (Mark Kirkwood, )
       Re: [HACKERS] Hints proposal  (Josh Berkus, )
        Re: [HACKERS] Hints proposal  ("Jim C. Nasby", )
         Re: [HACKERS] Hints proposal  (Alvaro Herrera, )
         Re: [HACKERS] Hints proposal  (Tom Lane, )
      Re: [HACKERS] Hints proposal  (Gregory Stark, )
    Re: Hints proposal  ("Craig A. James", )
    Re: [HACKERS] Hints proposal  ("Zeugswetter Andreas ADI SD", )
  Re: Hints proposal  (Csaba Nagy, )
   Re: [HACKERS] Hints proposal  (Josh Berkus, )
    Re: [HACKERS] Hints proposal  (Csaba Nagy, )
   Re: [HACKERS] Hints proposal  (Tom Lane, )
 Re: Hints proposal  (Jeff Davis, )
  Re: Hints proposal  (Csaba Nagy, )
   Re: Hints proposal  (Jeff Davis, )
    Re: Hints proposal  (Arjen van der Meijden, )
     Re: Hints proposal  (Tom Lane, )
      Re: Hints proposal  (Jeff Davis, )
     Re: Hints proposal  (Richard Broersma Jr, )
     Re: Hints proposal  (Christopher Browne, )
  Re: Hints proposal  ("Jim C. Nasby", )
   Re: Hints proposal  (Jeff Davis, )
 Re: [HACKERS] Hints proposal  (Andrew Sullivan, )
 Re: [HACKERS] Hints proposal  (Robert Treat, )

> 2d) Hints will damage the ongoing development of the optimizer by
> reducing or eliminating test cases for its improvement.

You have no evidence for this. The mindset of the postgres community you
cite further below usually mandates that you say things if you have
evidence for them... and this one could be even backwards, by putting
such a tool in normal mortals hands that they can experiment with
execution plans to see which one works better, thus giving more data to
the developers than it is possible now. This is of course a speculation
too, but not at all weaker than yours.

> 2e) Hints will divert developer resource away from ongoing development
> of the optimizer.

This is undebatable, although the long term cost/benefit is not clear.
And I would guess simple hinting would not need a genius to implement it
as planner optimizations mostly do... so it could possibly be done by
somebody else than the core planner hackers (is there any more of them
than Tom ?), and such not detract them too much from the planner
optimization tasks.

> 2f) Hints may demoralize the developer community - many of whom will
> have been attracted to Postgres precisely because this was a realm where
> crude solutions were discouraged.

I still don't get it why are you so against hints. Hints are a crude
solution only if you design them to be like that... otherwise they are
just yet another tool to get the work done, preferably now.

> I understand that these points may seem a bit 'feel-good' and intangible
> - especially for the DBA's moving to Pg from Oracle, but I think they
> illustrate the mindset of the Postgres developer community, and the
> developer community is, after all - the primary reason why Pg is such a
> good product.

I fail to see why would be a "hinted" postgres an inferior product...

> Of course - if we can find a way to define 'hint like' functionality
> that is more in keeping with the 'Postgres way' (e.g. some of the
> relation level statistical additions as discussed), then some of 2d-2f)
> need not apply.

I bet most of the users who wanted hints are perfectly fine with any
variations of it, if it solves the problems at hand.

Cheers,
Csaba.




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