| 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 |
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| 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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