RE: redo and undo

From: Paul Harrison <>
Date: Mon, 5 Mar 2012 10:30:59 -0600
Message-ID: <001001ccfaed$5957a110$0c06e330$>

I'm not concern on measuring the amount of redo generated. I was wondering why the log miner did not show the redo for the undo and index blocks.

Trying to learn how it all works.


-----Original Message-----
From: [] On Behalf Of David Fitzjarrell
Sent: Monday, March 05, 2012 10:16 AM
To:; Subject: Re: redo and undo

LlogMiner reports the SQL statements to redo or undo the change; it does not report the amoujnt of redo generated for the operation specified.  You would need to query the data dictionary for such statistics ( The v$mystat view would show the redo stats for your current session; query v$mystat, run the statement then query v$mystat again and take the difference -- you should see what you're expecting to see in terms of redo generation.  A query to do this is:

select, m.value
from v$mystat m join v$statname n on (n.statistic# = m.statistic#) where like 'redo%';

David Fitzjarrell

From: Paul Harrison <> To:
Sent: Monday, March 5, 2012 8:32 AM
Subject: redo and undo

Hi All,

Let's say I run the following command...  insert into cure.thecure (firstname ,lastname) values('oracle','11gr2'); The table has an index on the lastname column...

Using Log Miner, There is redo and undo for the table block.  The book I'm reading said that all 3 types of blocks (undo, table, index) have generated redo to protect them. I'm lost here because I do not see redo for the index block or the undo block. I only see redo and undo for the table block.

Any help is greatly appreciated.

Log Miner info below:

INSERT      insert into "CURE"."THECURE"("FIRSTNAME","LASTNAME") values ('oracle','11gr2');    delete from "CURE"."THECURE" where "FIRSTNAME" 'oracle' and "LASTNAME" = '11gr2' and ROWID = 'AAARlCAAEAAAAIMAAB';


Received on Mon Mar 05 2012 - 10:30:59 CST

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