|
|
by Craig Shallahamer Get the book here |
|
|
Craig Shallahamer's Blog
The text below is an except from the book, Oracle Performance Firefighting, written by Craig Shallahamer of OraPub, Inc. Figures and tables are not included on this page, only their reference. To order the book in either print or PDF form, click here. ©2009, 2010 by Craig Shallahamer. This is copyrighted material. Please—Out of respect for those involved in the creation of the book and also for their familes, we ask you to respect the copyright both in intent and deed. Thank you. ------------------------------- If IMU is causing problems, on Oracle Database 10g and later systems, you will see the wait event latch: In-memory undo latch as your top wait event. Plus your database server CPUs are probably so hot due to server processes spinning trying to acquire one of the IMU latches that they are ready to explode. So pinpoint diagnosis is not the tricky part. As with most latches, there are many possible problem resolution and performance optimization solutions. Here is a list of possible solutions: * Turn off IMU. Set _in_memory_undo to false. I've even seen Oracle support recommend this. It's a shame if you have to do this, but if it turns out there is a serious problem with the kernel code or how Oracle interacts with the operating system, you may need to completely disable IMU (and hope there is a patch). Please—Out of respect for those involved in the creation of the book and also for their familes, we ask you to respect the copyright both in intent and deed. Thank you. |
Know what's important before it's too late!
OraPub's
Performance Training
is like no other...
More Class Pics...
Get student testimonials!