RE: Please a parameter to disable undo, like _disable_logging

  • From: "Lex de Haan" <lex.de.haan@xxxxxxxxxxxxxx>
  • To: <Mark.Bobak@xxxxxxxxxxxxxxx>, <jreyes@xxxxxxxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 7 Oct 2004 09:31:54 +0200

you might want to check a certain hidden parameter
(with a rather straightforward name)
and change its value to TRUE ...
that is, the feature is indeed disabled by default
and there is no supported/documented way to enable it.

Kind regards,
Lex.
 
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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Bobak, Mark
Sent: Wednesday, October 06, 2004 20:40
To: jreyes@xxxxxxxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: Please a parameter to disable undo, like _disable_logging


I can't get it to work, either:
SQL> create table undo_Test nologging as select * from dba_objects;

Table created.

SQL> desc undo_test
 Name                                      Null?    Type
 ----------------------------------------- -------- =
----------------------------
 OWNER                                              VARCHAR2(30)
 OBJECT_NAME                                        VARCHAR2(128)
 SUBOBJECT_NAME                                     VARCHAR2(30)
 OBJECT_ID                                          NUMBER
 DATA_OBJECT_ID                                     NUMBER
 OBJECT_TYPE                                        VARCHAR2(18)
 CREATED                                            DATE
 LAST_DDL_TIME                                      DATE
 TIMESTAMP                                          VARCHAR2(19)
 STATUS                                             VARCHAR2(7)
 TEMPORARY                                          VARCHAR2(1)
 GENERATED                                          VARCHAR2(1)
 SECONDARY                                          VARCHAR2(1)

SQL> update undo_test set object_name =3D  'MJB';

40237 rows updated.

SQL> select used_ublk,used_urec from v$transaction where addr in(select =
taddr from v$session where sid=3D(select sid from v$mystat where =
rownum=3D1));

 USED_UBLK  USED_UREC
---------- ----------
       551      40238

SQL> rollback;

Rollback complete.

SQL> exec dbms_transaction.begin_discrete_transaction

PL/SQL procedure successfully completed.

SQL>  update undo_test set object_name =3D  'MJB';

40237 rows updated.

SQL> select used_ublk,used_urec from v$transaction where addr in(select =
taddr from v$session where sid=3D(select sid from v$mystat where =
rownum=3D1));

 USED_UBLK  USED_UREC
---------- ----------
       551      40237

Any thoughts or comments, Lex?  Or others?

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Juan Carlos Reyes
Pacheco
Sent: Wednesday, October 06, 2004 3:10 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: Please a parameter to disable undo, like _disable_logging


Based on my test=20
Begin discrete transaction don't work disabling undo information, =
because I
can see data before the commit.

SQL> exec DBMS_TRANSACTION.BEGIN_DISCRETE_TRANSACTION;
SQL> update test set object_name =3D 'a';
SQL> select distinct object_name from test;

OBJECT_NAME
-------------------------------------------------------------------------=
----


a



When there is not undo info you can't do that, for example append don't
generate undo info, and you can't see data
until you commit.

SQL> insert /*+ APPEND */ into test select * from dba_objects;
29291 rows created.
SQL> select distinct object_name from test;
select distinct object_name from test
                                 *
ERROR at line 1:
ORA-12838: no se puede leer/modificar un objeto despu=DAs de modificarlo =
en
paralelo




Or I'm wrong.

Thanks in advance.


Juan Carlos Reyes Pacheco
OCP
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