RE: redo and undo

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

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.

Thanks,
Paul

-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of David Fitzjarrell
Sent: Monday, March 05, 2012 10:16 AM
To: cure_at_austin.rr.com; Oracle-L_at_freelists.org 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 n.name, m.value
from v$mystat m join v$statname n on (n.statistic# = m.statistic#) where n.name like 'redo%';
 
 

David Fitzjarrell

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From: Paul Harrison <cure_at_austin.rr.com> To: Oracle-L_at_freelists.org
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:
OPERATION    SQL_REDO
SQL_UNDO

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

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