RE: waits
- From: "Baumgartel, Paul" <paul.baumgartel@xxxxxxxxxxxxxxxxx>
- To: joseph.armstrong-champ@xxxxxxxxx, oracle-l@xxxxxxxxxxxxx
- Date: Thu, 15 Nov 2007 10:23:00 -0500
Joe,
Start by running an ASH report or AWR report for a time period of
interest. See how much of total database service time is consumed by
the various waits. Identify the SQL that is associated with the top
waits. You may then wish to trace individual sessions (using
dbms_monitor) to determine the cause of poor performance. Inspect
execution plans, as the 10g optimizer is very different from 8i. Also
make sure that you have up-to-date statistics on tables and indexes.
Paul Baumgartel
CREDIT SUISSE
Information Technology
Securities Processing Databases Americas
One Madison Avenue
New York, NY 10010
USA
Phone 212.538.1143
paul.baumgartel@xxxxxxxxxxxxxxxxx
www.credit-suisse.com
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Joe Armstrong-Champ
Sent: Thursday, November 15, 2007 9:31 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: waits
We have been having performance issues since we upgraded from 8i to
10.2.0.3. OS is aix 5.2.
Someone showed me the results from a query against v$system_event but
I'm not sure if the number of waits or the average waits is high. Can
anyone comment about this or tell me where I can find info about what
numbers are "too high"? :
EVENT TOTAL_WAITS TIME_WAITED AVERAGE_WAIT
----------------------------------------------------------------
db file parallel read 1959 1988 1.01
latch: shared pool 135658 226721 1.67
latch free 11828 19785 1.67
latch: cache buffers chains 5735 13096 2.28
latch: library cache 140371 719066 5.12
log file sequential read 1398 8014 5.73
Thanks.
Joe
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