RE: why does block cleanout incur redo?

It's because "flush" doesn't mean what you probably think. During a delayed block cleanout, Oracle updates a block's transaction table (ITL). Any time a block gets modified, there's redo.  

See Jonathan Lewis's Practical Oracle8i (pp43-44) for a description.  

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com

Upcoming events:
- Hotsos Clinic <http://www.hotsos.com/training/clinic101> 101 in
Denver, Sydney
- Hotsos Symposium 2004 <http://www.hotsos.com/events/symposium/2004>
March 7-10 Dallas
- Visit www.hotsos.com for schedule details...

-----Original Message-----
Ryan
Sent: Wednesday, August 06, 2003 9:34 PM To: Multiple recipients of list ORACLE-L  

My understanding of block cleanout is that oracle is flushing transaction information of already committed transactions from the buffer cache. This can happen in selects, when 10% of the buffer cache is filled with 'lists' if blocks involved in transactions, or with dml.  

i dont understand why this incurs redo? your just flushing blocks that are no longer needed?

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Cary Millsap
  INET: cary.millsap_at_hotsos.com

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).