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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jim C. Nasby <decibel@decibel.org>
Cc: Neil Conway <neilc@samurai.com>
Cc: Christopher Petrilli <petrilli@gmail.com>
Cc: Ying Lu <ying_lu@cs.concordia.ca>
Cc: pgsql-general@postgresql.org
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] "Hash index" vs. "b-tree index" (PostgreSQL
Date: Tue, 10 May 2005 14:07:00 -0400
Message-ID: <20884.1115748420@sss.pgh.pa.us> (raw)
In-Reply-To: <20050510153245.GA31103@decibel.org>
References: <427F6853.90308@cs.concordia.ca>
	<427F757A.8000407@samurai.com>
	<59d991c405050908271b55e673@mail.gmail.com>
	<427F8321.5030702@samurai.com>
	<20050509163423.GH35026@decibel.org>
	<427F9211.2090008@samurai.com>
	<20050509165133.GJ35026@decibel.org>
	<427FFCD3.1010803@samurai.com>
	<20050510153245.GA31103@decibel.org>

"Jim C. Nasby" <decibel@decibel.org> writes:
> Well, in a hash-join right now you normally end up feeding at least one
> side of the join with a seqscan. Wouldn't it speed things up
> considerably if you could look up hashes in the hash index instead?

That's called a "nestloop with inner index scan", not a hash join.

			regards, tom lane



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