“ITL is blanked by the DML session only if the block is still in the cache”. Doesn’t it work in conjunction with a parameter that defines the dirty block threshold? Regards Raj From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of vit.spinka Sent: Friday, January 08, 2010 12:01 PM To: oracle-l@xxxxxxxxxxxxx Cc: Martin.Klier@xxxxxxxxxx Subject: Re: How are ITL entries banked? Hi Martin, the acutal algortihm is in fact a bit complicated; if I simplify it, then the ITL is blanked by the DML session only if the block is still in the cache. This is the "fast commit" cleanout. If it's already on the disk, than it's blanked by any other session that reads it from the disk next time. The session checks the undo if the referenced XID is till active; if not, the commit SCN of that XID is used to blank the ITL. If the XID is no longer in undo, we can safely assume the transaction already commited and blank the ITL as well (using lowest SCN of any active transaction). This is the "delayed block cleanout". Note that blanking the ITL also involves setting the commit SCN of that particular row, so we can properly answer any read-consistent queries. Further details are described at http://www.jlcomp.demon.co.uk/cleanout.html . Vit Spinka This communication is for informational purposes only. It is not intended as an offer or solicitation for the purchase or sale of any financial instrument or as an official confirmation of any transaction. All market prices, data and other information are not warranted as to completeness or accuracy and are subject to change without notice. Any comments or statements made herein do not necessarily reflect those of JPMorgan Chase & Co., its subsidiaries and affiliates. This transmission may contain information that is privileged, confidential, legally privileged, and/or exempt from disclosure under applicable law. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution, or use of the information contained herein (including any reliance thereon) is STRICTLY PROHIBITED. Although this transmission and any attachments are believed to be free of any virus or other defect that might affect any computer system into which it is received and opened, it is the responsibility of the recipient to ensure that it is virus free and no responsibility is accepted by JPMorgan Chase & Co., its subsidiaries and affiliates, as applicable, for any loss or damage arising in any way from its use. If you received this transmission in error, please immediately contact the sender and destroy the material in its entirety, whether in electronic or hard copy format. Thank you. Please refer to http://www.jpmorgan.com/pages/disclosures for disclosures relating to European legal entities.