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library cache [message #387031] Tue, 17 February 2009 11:30 Go to next message
caprikar
Messages: 226
Registered: March 2007
Senior Member
Hi,
I have oracle 10g RAC on HP-UX. We had a performance problem sometime ago and I see lot of library cache in Grid. Can some one tell me how to find what is causing the library cache and which is the hot object is?
Thanks
Re: library cache [message #387034 is a reply to message #387031] Tue, 17 February 2009 11:51 Go to previous messageGo to next message
BlackSwan
Messages: 25033
Registered: January 2009
Location: SoCal
Senior Member
You need to help us by following the Posting Guidelines as stated below.
http://www.orafaq.com/forum/t/88153/0/
So we can help you

http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/toc.htm



>Can some one tell me how to find what is causing the library cache and which is the hot object is?

What evidence/proof do you have that library cache is part of the problem & not just an observation of reality.

The library cache is a necessary part of Oracle's implementation.
Yes, it is used by Oracle, otherwise it would not exist.

In My Opinion, you do not tune Oracle at the macro level (Database).
You tune the database 1 SQL statement at a time.
If/when Oracle has no SQL, it sits idle.
When you have poor performance, you tune the SQL which is not performing well.

[Updated on: Tue, 17 February 2009 12:00]

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Re: library cache [message #387044 is a reply to message #387031] Tue, 17 February 2009 13:08 Go to previous messageGo to next message
caprikar
Messages: 226
Registered: March 2007
Senior Member
When i ran the ASH report it was showing that 85% of wait event was library cache. You are right, I need to tune the application for which I was trying to get the sql that was causing the library cache contention. My question was how do i get the information on which sql is causing the library cache contention
Re: library cache [message #387046 is a reply to message #387031] Tue, 17 February 2009 13:33 Go to previous messageGo to next message
BlackSwan
Messages: 25033
Registered: January 2009
Location: SoCal
Senior Member
>how do i get the information on which sql is causing the library cache contention
What evidence/proof do you have that library cache is part of the problem & not just an observation of reality.

>When i ran the ASH report it was showing that 85% of wait event was library cache.
Meaningless percentage?

If "wait event" is only 5% of elapsed time, then reducing "wait event" to zero still will NOT produce much of a change.

Tune the long running or resource intensive SQL statements
Re: library cache [message #387059 is a reply to message #387046] Tue, 17 February 2009 15:51 Go to previous message
caprikar
Messages: 226
Registered: March 2007
Senior Member
Not 5% it was 85%
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