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

From: Jim C. Nasby
Subject: Re: [PERFORM] "Hash index" vs. "b-tree index" (PostgreSQL
Date: ,
Msg-id: 20050509165133.GJ35026@decibel.org
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In response to: Re: [PERFORM] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway)
Responses: Re: [PERFORM] "Hash index" vs. "b-tree index" (PostgreSQL  (Neil Conway)
Re: [PERFORM] "Hash index" vs. "b-tree index" (PostgreSQL  (Bruce Momjian)
List: pgsql-general

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

On Tue, May 10, 2005 at 02:38:41AM +1000, Neil Conway wrote:
> Jim C. Nasby wrote:
> >Having indexes that people shouldn't be using does add confusion for
> >users, and presents the opportunity for foot-shooting.
>
> Emitting a warning/notice on hash-index creation is something I've
> suggested in the past -- that would be fine with me.

Probably not a bad idea.

> >Even if there is some kind of advantage (would they possibly speed up
> >hash joins?)
>
> No, hash joins and hash indexes are unrelated.

I know they are now, but does that have to be the case? Like I said, I
don't know the history, so I don't know why we even have them to begin
with.
--
Jim C. Nasby, Database Consultant               
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