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RE: Redo Logfile content- (A)SQL Statements OR (B)Modified Data Block OR (C)BOTH

From: Jankovic, Djordje <Djordje.Jankovic_at_attcanada.com>
Date: Mon, 05 May 2003 06:56:41 -0800
Message-ID: <F001.0058F6A6.20030505065641@fatcity.com>


Redo contains the modifications, and not the statement you ran. From Logminer you do not see the statement you ran but you see all the atomic changes that happened reverse engineered to statements that would re-apply individual changes.  

BTW redo log files contain the rollback blocks as well.  

Djordje

-----Original Message-----
Sent: Monday, May 05, 2003 3:07 AM
To: Multiple recipients of list ORACLE-L Block OR (C)BOTH

Dear All DBAs,

I've a very basic doubt. I got size of 300MB archive redo logfile for "one create table" statement.

What do we have in Redo Log File?
(A)SQL Statements OR (B)Modified Data Block OR (C)
BOTH. Kindly look at case study below.

Oracle 9iR2 Windows NT ARCHIVE LOG Mode


Tablespace info:-

Name                                                   : EXAMPLE
Datafile Name                                  : example01.dbf
Extent_management                 : LOCAL
Allocation_type                                  : SYSTEM
Segment_Space_Management: AUTO
Default Tablespace of                 : HR

1)Original example01.dbf datafile size 500MB;

2)create table HR.T2 pctfree 99 pctused 1 as select * from dba_objects;

                (used PCTFREE 99 to increase the table size by
absorbing more number of blocks)

3)

SQL> select count(*) from t2;

 COUNT(*)


    38085

SQL> select bytes,blocks,extents from dba_segments where segment_name='T2' and owner='HR';

    BYTES BLOCKS EXTENTS
---------- ---------- ----------
318767104 38912 109

4)After table creation, example01.dbf datafile size becomes 800MB;

                (datafile size got increased because of Table T2
creation)

Q1) How much archive will be generated between step(1) and step(4).
(Assume that this is the only activity happened in the
DB)

Here 60 number of 5MB archive files got
generated(close to 300 MB).

My question about Redo log file-->
(A) Does it have actual modified blocks? OR

OR

(B) Does it have just the stament which has been used
to modify the datablocks?

                (Using LogMiner I see only statements)
OR

(C) BOTH

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jankovic, Djordje
  INET: Djordje.Jankovic_at_attcanada.com

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Received on Mon May 05 2003 - 09:56:41 CDT

Original text of this message

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