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user3266490 wrote:It appears that you suffer from Compulsive Tuning Disorder.
We getting below wait event in db.what i have to do
Have a cup of tea & ignore this result set.
You need to learn to mark your questions as answered
Status Level: Newbie (25)
Registered: Nov 26, 2008
Total Posts: 1,362
Total Questions: 799 (652 unresolved)
It appears that you suffer from Compulsive Tuning Disorderwhat is the meaning?
Could you tell why the above result should i ignore?
Thanks & Regards,
Edited by: user3266490 on Nov 26, 2012 4:47 AM
We getting below wait event in db.what i have to do1) v$ views show accumulated stats since instance startup, which means that the numbers you posted don't give us the full picture. Has your instance been running for an hour, a day, a week, a month, a year? What is the DB time to elapsed time ratio (average number of active sessions)? Without additional context, wait event dumps are often rather misleading than helpful
EVENT TOTAL_WAITS TOTAL_TIMEOUTS TIME_WAITED
------------------------------ ----------- -------------- -----------
db file sequential read 925803300 0 877516576
library cache lock 291405693 0 584484549
library cache: mutex X 838924416 0 538332419
2) since we don't have DB time or wall clock time, let's use the total wait time for the biggest wait event to set the scale. library cache lock and library cache: mutex X events combined are responsible for more wait time than db file sequential read, which suggests that you do have a problem
3) these waits indicate high level of library cache contention which often happens when you do too much of the following:
- hard parsing
- soft parsing
- cursor invalidation (e.g. by performing DDL on live schema or gathering stats)
- resize shared pool
4) the best course of action would be to collect some meaningful diagnostic data, like an AWR report for a busy hour (if you have the Diagnostic Pack License; if you don't, use statspack) and post following sections:
- header (report time, num CPUs, platform and other info)
- load profile
- top timed events
- time model statistics
5) be sure to use
tags when posting anything, it really doesn't look good when someone makes his/her 1,363th post without properly formatting SQL and it's output Best regards, Nikolay