RE: How are ITL entries banked?

  • From: Rajesh Rao <Rajesh.Rao@xxxxxxxxxxxx>
  • To: "vit.spinka@xxxxxxxxxxxx" <vit.spinka@xxxxxxxxxxxx>, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 8 Jan 2010 12:23:46 -0500

“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 


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 .

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 for
disclosures relating to European legal entities.

Other related posts: