RE: redo and undo

-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Riyaj Shamsudeen
Sent: Monday, March 05, 2012 10:40 AM
To: cure_at_austin.rr.com
Cc: oratune_at_yahoo.com; Oracle-L_at_freelists.org Subject: Re: redo and undo

Paul
  Log miner is only mining for changes to replay. Index changes are recursive and does not show up.
 Yes, there will be redo change vectors for index block changes, undo for that index block change, and changes to undo block headers (if this is begin or end of a transaction) etc.

  I have a paper about this topic:

http://www.orainternals.com/wp-content/uploads/2011/12/Riyaj_redo_internals_ and_tuning_by_redo_reduction_doc.pdf

Cheers

Riyaj Shamsudeen
Principal DBA,
Ora!nternals - http://www.orainternals.com - Specialists in Performance, RAC and EBS
Blog: http://orainternals.wordpress.com
OakTable member http://www.oaktable.com and Oracle ACE Director

Co-author of the books: Expert Oracle
Practices<http://tinyurl.com/book-expert-oracle-practices/>, Pro Oracle SQL, Expert PL/SQL
Practices<http://tinyurl.com/book-expert-plsql-practices>

Join me for next RAC training in March
2012<http://www.orainternals.com/services/training/advanced-rac-training/>:

<http://tinyurl.com/book-expert-plsql-practices>

On Mon, Mar 5, 2012 at 10:30 AM, Paul Harrison <cure_at_austin.rr.com> wrote:

> 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
>
>
>
> ________________________________
> 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
> ------------
>
> ----------------------------------------------------------------------
> ------
> -----
>
> ----------------------------------------------------------------------
> ------
> ------------------------
> 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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