Re: [GENERAL] hash taboo? - Mailing list pgsql-general

From Bruce Momjian
Subject Re: [GENERAL] hash taboo?
Date
Msg-id 199912180324.WAA03818@candle.pha.pa.us
Whole thread Raw
In response to hash taboo?  (admin <admin@wtbwts.com>)
Responses Re: [GENERAL] hash taboo?  (admin <admin@wtbwts.com>)
List pgsql-general
Run some performace tests and let us know.

> I've been reading the postgresql manual and I find there is very little
> discussion about hash compared to btree. Most of the focus seems to be on
> using btree indices even that the default for 'create index' is btree
> also. From the documentation, it seems the only difference between either
> searching method is that btree can be used with multiple operators whilst
> hash can only be used with '='. Furthermore, hash seems to be contained in
> memory, so should be limited to small queries or, in my case, queries
> using limit (without using sort which would need to retrieve the entire
> data anyways).
>
> My conclusion is that if I can live with just using '=' and using slightly
> more memory, I should be using hash. Unfortunately, there is very little
> sign in the documentation that I should be using hash at all. Perhaps I
> have missed something important.
>
> If someone could help me make a more rational decision on using searching
> methods, I'd appreciate.
>
> Thanks in advance,
> Marc
>
>
> ************
>
>


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