When Parallel Doesn't Happen

From: Kellyn Pedersen <kjped1313_at_yahoo.com>
Date: Thu, 1 Oct 2009 09:45:38 -0700 (PDT)
Message-ID: <35396.35827.qm_at_web32006.mail.mud.yahoo.com>

I have just started for a company that applies to the philosophy of too much of a good thing is really a good thing, so bear with me...
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The code has parallel hints everywhere- degrees often set to 8 in multiple hints in one DML or DDL set, (parallel_threads_per_cpu=2, so start doing the math...)� The parallel_server is set� anywhere from 96 to 168 and someone had the idea that as long as they set the threshold high enough, everything would run.�
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I have never seen parallel used the way it is here and I've come across some very interesting challenges.� The amount of slaves being allocated to a process are being downgraded as resources are becoming limited by the poor choices made in some of these simultaneous requests.
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queries parallelized����������������������������� 10443
DDL statements parallelized������������������� 106
DFO trees parallelized�������������������� 10549

Parallel operations not downgraded�� 10457 Parallel operations downgraded to serial�19

Parallel operations downgraded 75 to 99 pct�0
Parallel operations downgraded 50 to 75 pct�0
Parallel operations downgraded 25 to 50 pct�92

Parallel operations downgraded 1 to 25 pct�0 PX local messages sent�205011362
PX local messages recv'd�230002397
PX remote messages sent�0
PX remote messages recv'd�0
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Received on Thu Oct 01 2009 - 11:45:38 CDT