Re: "Hash index" vs. "b-tree index" (PostgreSQL 8.0) - Mailing list pgsql-general

From Neil Conway
Subject Re: "Hash index" vs. "b-tree index" (PostgreSQL 8.0)
Date
Msg-id 427F757A.8000407@samurai.com
Whole thread Raw
In response to "Hash index" vs. "b-tree index" (PostgreSQL 8.0)  (Ying Lu <ying_lu@cs.concordia.ca>)
Responses Re: [PERFORM] "Hash index" vs. "b-tree index" (PostgreSQL 8.0)  (Christopher Petrilli <petrilli@gmail.com>)
List pgsql-general
Ying Lu wrote:
> May I know for simple "=" operation query, for "Hash index" vs. "B-tree"
> index, which can provide better performance please?

I don't think we've found a case in which the hash index code
outperforms B+-tree indexes, even for "=". The hash index code also has
a number of additional issues: for example, it isn't WAL safe, it has
relatively poor concurrency, and creating a hash index is significantly
slower than creating a b+-tree index.

-Neil

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