LOB and retention

Question

Hi,
I try to modify the retention parameter on a partition table. Whatever the SQL order, I ran ... I can't see the result in the dictionary. What's wrong in my sql order ?
Thanks a lot for your help ..
The release of the database is 9.2.0.8.
I create the table:
==============
CREATE TABLE test_lob (chp1 clob, chp2 int)
lob (chp1) STORE AS SEGNAME (TABLESPACE FD
PCTVERSION 0)
partition by range (chp2)
(PARTITION P1 VALUES LESS THAN (1),
PARTITION P2 VALUES LESS THAN (2),
PARTITION P3 VALUES LESS THAN (3));
I verify that the value is correct in the dictionary:
===================================
select bitand(defflags,32) from sys.partlob$ where TABOBJ# in(select OBJECT_ID from dba_objects where OBJECT_NAME='TEST_LOB');
(result is 0)
I modify the table:
===============
alter table test_lob modify lob(chp1) (retention);
I check one more time:
==================
select bitand(defflags,32) from sys.partlob$ where TABOBJ# in(select OBJECT_ID from dba_objects where OBJECT_NAME='TEST_LOB');
(result is 0 .. must be 32)
I make another SQL order:
====================
alter table test_lob modify partition p1 lob (chp1) (retention);
alter table test_lob modify partition p2 lob (chp1) (retention);
alter table test_lob modify partition p3 lob (chp1) (retention);
I check one more time :
====================
select bitand(defflags,32) from sys.partlob$ where TABOBJ# in(select OBJECT_ID from dba_objects where OBJECT_NAME='TEST_LOB');
(result is 0 .. must be 32)
What's wrong ???

Answer 1

Before I checked the 10g manual I would have said that LOB segments do not use UNDO tablespace. UNDO for LOB segments is kept in the LOB segment.
>>
PCTVERSION integer Specify the maximum percentage of overall LOB storage space used for maintaining old versions of the LOB. The default value is 10, meaning that older versions of the LOB data are not overwritten until they consume 10% of the overall LOB storage space.
You can specify the PCTVERSION parameter whether the database is running in manual or automatic undo mode. PCTVERSION is the default in manual undo mode. RETENTION is the default in automatic undo mode. You cannot specify both PCTVERSION and RETENTION.
RETENTION Use this clause to indicate that Oracle Database should retain old versions of this LOB column. Oracle Database uses the value of the UNDO_RETENTION initialization parameter to determine the amount of committed undo data to retain in the database.
You can specify the RETENTION parameter only if the database is running in automatic undo mode. In this mode, RETENTION is the default value unless you specify PCTVERSION. You cannot specify both PCTVERSION and RETENTION
<<
I still believe that when RETENTION is set that Oracle uses the LOB segment to store the UNDO rather than the UNDO tablespace, but I will have to see the documentation in more detail to try to find support.
HTH -- Mark D Powell --