You were brought to this page based on an internet search
and as a free service to Oracle DBAs.
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.
PleaseOut 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.
-------------------------------
* Check for cloning issues. Whenever I encounter CBC latch contention, I check to ensure cloning is not the issue. This is rarely the case, but if it is, the solution path (as outlined previously) is very different from all the other solutions.
* Increase CBC latches. This usually brings some relief, but not nearly as much as tuning the logical IO SQL. The hidden instance parameter _db_block_hash_latches controls the number of CBC latches. Before you change this, be aware there may be support issues from both Oracle and your application vendor.
* Increase CBC buckets. This rarely brings any performance relief because Oracle, by default, creates a tremendous number of buckets. Unless someone previously decreased the number of CBC buckets, increasing this parameter will probably have little effect on performance.
©2009, 2010 by Craig Shallahamer. This is copyrighted material.
PleaseOut 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.
|