|
|
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. ------------------------------- * ---- means the transaction is active; that is, DML is occurring and the transaction has not been committed or rolled back. * --U- means the transaction has committed, so any row data referencing the ITL is not involved in an active transaction and is therefore not locked. The transaction's row data may not be consolidated. By consolidated I mean, for example, if a column was updated, both the before and after values can remain in the row data. * C--- means the transaction has been committed, row data has been consolidated, and the ITL entry in the row data has been removed. Any block touch can (but does not always) trigger the change to this flag value, including a select statement. I realize this is difficult to believe, so I will demonstrate it shortly. This seemingly delayed change is commonly referred to as a delayed block cleanout, or simply a block cleanout. 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!