Skip site navigation (1) Skip section navigation (2)

Re: Proposed Patch to Improve Performance ofMulti-BatchHash Join for Skewed Data Sets

From: Joshua Tolley <eggyknap(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>,"Lawrence, Ramon" <ramon(dot)lawrence(at)ubc(dot)ca>,Bryce Cutt <pandasuit(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: Proposed Patch to Improve Performance ofMulti-BatchHash Join for Skewed Data Sets
Date: 2009-02-26 14:57:25
Message-ID: 20090226145724.GE6811@eddie (view raw or flat)
Thread:
Lists: pgsql-hackers
On Thu, Feb 26, 2009 at 08:22:52AM -0500, Robert Haas wrote:
> On Thu, Feb 26, 2009 at 4:22 AM, Heikki Linnakangas
> <heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> > Joshua, in the tests that you've been running, did you have to rig the
> > planner with "enable_mergjoin=off" or similar, to get the queries to use
> > hash joins?
> 
> I didn't have to fiddle anything, but Josh's tests were more exhaustive.

The planner chose hash joins for the queries I was running, regardless
of whether the patch was applied. I didn't have to mess with any
settings to get hash joins.

- Josh

In response to

Responses

pgsql-hackers by date

Next:From: David FetterDate: 2009-02-26 15:23:35
Subject: Re: Have \d show child tables that inherit from thespecified parent
Previous:From: Robert HaasDate: 2009-02-26 14:54:18
Subject: Re: 8.4 release planning (was Re: [COMMITTERS] pgsql: Automatic view update rules)

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group