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Re: parallel hint with group by gives wrong results

From: John D Parker <orclwzrd_at_yahoo.com>
Date: Fri, 21 Dec 2007 07:02:45 -0800 (PST)
Message-ID: <181445.22103.qm@web32603.mail.mud.yahoo.com>


Bad me, the version is 10.2.0.3 with various sundry one off's applied. I'm leaning toward the combination of star transform and parallel hint being the issue.

What really bugs me is client is reporting problem with only one query out of thousands... watcha bet they haven't bench checked the reports for correctness.

John

K Gopalakrishnan <kaygopal_at_gmail.com> wrote: No version details..Assume 10gR2.. If yes you are probably hitting some interesting bugs are hash aggregation.. Does your plan have 'HASH GROUP BY'? -Gopal

On Dec 20, 2007 11:53 AM, John D Parker wrote:
> query with no parallel hint and parallel degree 7 set on some of the
> tables(including table that is hinted) gives right answer but is "too slow"
>
> query with parallel hint and no specified degree(ie default degree) and
> parallel degree 7 set on some of the tables(including table that is hinted)
> gives wrong answer by factor of default degree and is fast enough.
>
> The query has a sum and a group by, the sum is off by multiple of the
> default degree(24) when the parallel hint is given. Anyone know about any
> "features" relating to sum/group by/parallel hint/default degree.
>
> all help welcome.
>
> john
>
>
> ________________________________
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-- 
Best Regards,
K Gopalakrishnan
Co-Author: Oracle Wait Interface, Oracle Press 2004
http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/

Author: Oracle Database 10g RAC Handbook, Oracle Press 2006
http://www.amazon.com/gp/product/007146509X/
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Received on Fri Dec 21 2007 - 09:02:45 CST

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