Just the previous version of the changed columns,
plus an overhead of about 80 bytes which relates
to ITLs, linked lists, operation descriptions etc.

Bear in mind that undo relating to indexes is not
the same as undo relating to tables, though.  An
update to an indexed column results in one index
entry being deleted (so the whole index entry 
is coped to the undo) and another index entry
being inserted (which also means the whole (new)
index entry being copied to the undo).

There is a statistic relating to undo size in v$sysstat/v$sesstat
in the most recent versions of Oracle.

While a transaction is active, you can track it in v$transaction,
and there are two columns in that view giving you information
about the undo - used_urec (undo records created) and used_ublk
(undo block used).

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

  The educated person is not the person 
  who can answer the questions, but the 
  person who can question the answers -- T. Schick Jr


One-day tutorials:
http://www.jlcomp.demon.co.uk/tutorial.html


Three-day seminar:
see http://www.jlcomp.demon.co.uk/seminar.html
____UK___November


The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html


----- Original Message ----- 
To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]>
Sent: Wednesday, December 24, 2003 8:44 PM


> I have a related  question : What about update? In rollback segment : 
> Will it store the whole row for before image or just the changed column 
> and rowid. Is there a way to get the size of the rollback from some 
> where in the database. or v$ views. Like we can get an idea about redo 
> size from redo log files generated. Thank you
> 
> 

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jonathan Lewis
  INET: [EMAIL PROTECTED]

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: [EMAIL PROTECTED] (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).

Reply via email to