Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL

От: Jim C. Nasby
Тема: Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL
Дата: ,
Msg-id: 20050509163423.GH35026@decibel.org
(см: обсуждение, исходный текст)
Ответ на: Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway)
Ответы: Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway)
Список: pgsql-performance

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"Hash index" vs. "b-tree index" (PostgreSQL 8.0)  (Ying Lu, )
 Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL 8.0)  (Neil Conway, )
  Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL 8.0)  (Christopher Petrilli, )
   Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway, )
    Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  ("Jim C. Nasby", )
     Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway, )
      Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  ("Jim C. Nasby", )
       Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway, )
        Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
         Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway, )
          Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
           Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway, )
           Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Greg Stark, )
            Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
             Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Greg Stark, )
              Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
               Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Greg Stark, )
                Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
                 Federated PG servers -- Was: Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Mischa Sandberg, )
         Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  ("Jim C. Nasby", )
          Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
           Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  ("Jim C. Nasby", )
            Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Mischa Sandberg, )
        Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  ("Jim C. Nasby", )
         Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
         Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Mischa Sandberg, )
          Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Mark Lewis, )
          Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
           Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Mischa Sandberg, )
       Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Bruce Momjian, )
 Re: "Hash index" vs. "b-tree index" (PostgreSQL 8.0)  (David Roussel, )
 Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Tom Lane, )
  Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway, )
 Re: [GENERAL] "Hash index" vs. "b-tree index" (PostgreSQL  (Greg Stark, )

On Tue, May 10, 2005 at 01:34:57AM +1000, Neil Conway wrote:
> Christopher Petrilli wrote:
> >This being the case, is there ever ANY reason for someone to use it?
>
> Well, someone might fix it up at some point in the future. I don't think
> there's anything fundamentally wrong with hash indexes, it is just that
> the current implementation is a bit lacking.
>
> >If not, then shouldn't we consider deprecating it and eventually
> >removing it.
>
> I would personally consider the code to be deprecated already.
>
> I don't think there is much to be gained b removing it: the code is
> pretty isolated from the rest of the tree, and (IMHO) not a significant
> maintenance burden.

That may be true, but it's also a somewhat 'developer-centric' view. ;)

Having indexes that people shouldn't be using does add confusion for
users, and presents the opportunity for foot-shooting. I don't know what
purpose they once served, but if there's no advantage to them they
should be officially depricated and eventually removed. Even if there is
some kind of advantage (would they possibly speed up hash joins?), if
there's no plans to fix them they should still be removed. If someone
ever really wanted to do something with, the code would still be in CVS.
--
Jim C. Nasby, Database Consultant               
Give your computer some brain candy! www.distributed.net Team #1828

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