RE: Suggestions Needed: Latch free - library cache

One way is by writing applications that use persistent connections. A mid-tier program ignites at 8am Jan 1, connects to the Oracle instance, and then parses all the SQL it will use for the remainder of the year. The interface to this program from the user side is via “services,” like “hire an employee,” “fire an employee,” “look up a salary,” or whatever. Thousands of users throughout the year use the services, but the only parse calls the application makes all year occurred during the first few minutes of the morning on New Year’s Day.

Advantages are huge if you eliminate what would otherwise have been thousands of connections/disconnections and parse calls per day. All the db gets are binds, executes, and fetches except for the first few minutes after instance start-up.

-----Original Message-----
From: ml-errors@fatcity.com [mailto:ml-errors@fatcity.com] On Behalf Of Ryan
Sent: Wednesday, January 07, 2004 6:15 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: Suggestions Needed: Latch free - library cache

----- Original Message -----

From: Bobak, Mark

To: Multiple recipients of list ORACLE-L

Sent: Wednesday, January 07, 2004 5:59 PM

Subject: RE: Suggestions Needed: Latch free - library cache

 

Tracy,

 

What Oracle version?  If you're not patched up to the latest patchset for your release, it's always a good idea to do so, as library cache bugs seem to invariably appear in every release.

 

Has your code changed recently?  Has your usage increased recently?

 

Finally, library cache latch contention can be a sign of excessive soft parsing (hard parsing usually causes more shared pool latch contention).  Do you have session_cached_cursors set?

 

Just some thoughts....

 

-Mark

 

 

Mark J. Bobak
Oracle DBA
ProQuest Company
Ann Arbor, MI
"Imagination was given to man to compensate him for what he is not, and a sense of humor was provided to console him for what he is."  --Unknown

-----Original Message-----
From: Tracy Rahmlow [mailto:tracy.rahmlow@aexp.com]
Sent: Wednesday, January 07, 2004 5:40 PM
To: Multiple recipients of list ORACLE-L
Subject: Suggestions Needed: Latch free - library cache

We have experienced intermittent problems (slow response time) with our oltp database today.  There appears to be a large number of latch free events and the p2 parameter is indicating an issue with the library cache.  Any thoughts on where to go next?

American Express made the following
annotations on 01/07/2004 03:36:25 PM
------------------------------------------------------------------------------
******************************************************************************

"This message and any attachments are solely for the intended recipient and may contain confidential or privileged information. If you are not the intended recipient, any disclosure, copying, use, or distribution of the information included in this message and any attachments is prohibited. If you have received this communication in error, please notify us by reply e-mail and immediately and permanently delete this message and any attachments. Thank you."

******************************************************************************


==============================================================================