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Re: updated hash functions for postgresql v1

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: CK Tan <cktan(at)greenplum(dot)com>
Cc: Luke Lonergan <LLonergan(at)greenplum(dot)com>, Kenneth Marshall <ktm(at)rice(dot)edu>, pgsql-patches(at)postgresql(dot)org, twraney(at)comcast(dot)net, neilc(at)samurai(dot)com
Subject: Re: updated hash functions for postgresql v1
Date: 2007-10-28 20:45:21
Message-ID: 1193604321.4242.740.camel@ebony.site (view raw or flat)
Thread:
Lists: pgsql-patches
On Sun, 2007-10-28 at 13:19 -0700, CK Tan wrote:
> Hi, this query on TPCH 1G data gets about 5% improvement.

> select count (*) from (select l_orderkey, l_partkey, l_comment,
> count(l_tax) from lineitem group by 1, 2, 3) tmpt;

> On Oct 28, 2007, at 1:17 PM, Luke Lonergan wrote:
> 
> > We just applied this and saw a 5 percent speedup on a hash
> > aggregation query with four colums in a 'group by' clause run
> > against a single TPC-H table (lineitem).
> > 
> > CK - can you post the query? 

Is this on Postgres or Greenplum?


That looks like quite a wide set of columns.

Sounds good though. Can we get any more measurements in?

-- 
  Simon Riggs
  2ndQuadrant  http://www.2ndQuadrant.com


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