RE: 9.2 - Parallel Query Not Working
- From: <krish.hariharan@xxxxxxxxxxxx>
- To: <david@xxxxxxxxxxxxxxxxxx>, <RS2273@xxxxxxx>, <mwf@xxxxxxxx>, "'Oracle List'" <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 28 Feb 2008 14:10:48 -0700
Out of curiosity
1. Are the execution plans the same (using explain plan and
sql_trace/10046)
2. I wonder if you could use 10053 to determine the decision taken the
by the optimizer
3. Are the statistics the same
Regards,
-Krish
Krish Hariharan
President/Executive Architect, Quasar Database Technologies, LLC
http://www.linkedin.com/in/quasardb
_____
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of David Aldridge
Sent: Thursday, February 28, 2008 1:57 PM
To: RS2273@xxxxxxx; mwf@xxxxxxxx; Oracle List
Subject: RE: 9.2 - Parallel Query Not Working
No, not RAC.
"Shamsudeen, Riyaj" <RS2273@xxxxxxx> wrote:
David
Is this RAC? Can you print exactly values for
parallel_instance_group and instance_groups?
_____
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Mark W. Farnham
Sent: Thursday, February 28, 2008 11:17 AM
To: david@xxxxxxxxxxxxxxxxxx; 'Oracle List'
Subject: RE: 9.2 - Parallel Query Not Working
How much of that table is already in the buffer cache when PQ stops being
operative?
mwf
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From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of David Aldridge
Sent: Thursday, February 28, 2008 12:03 PM
To: Oracle List
Subject: 9.2 - Parallel Query Not Working
On a 9.2.0.6 database on Solarix 64, which is created every day from a
magical SAN-based mirror process thing (excuse the tech talk), we alter a
particular table to a default degree of parallelsim of 12. A process which
performs a full scan of that table picks up the degree of 12 and completes
in a couple of hours.
Later in the day we can no longer prompt the instance to give any
parallelism.
I've tried everything obvious ... setting parallel_adaptive_multiuser to
false, parallel max servers to 48, used hints, made sure the table's default
dop is 12, checked that PROCESSES is reasonably high (500+), that the server
is not very busy (less than 10 active sessions), ALTER SESSION FORCE
PARALLEL QUERY, but nothing we do will prompt PQ to be used on even the most
simple SELECT * FROM ... queries.
Any thoughts on this are much appreciated.
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