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Home -> Community -> Mailing Lists -> Oracle-L -> Update: Deferred Rollback Segments
I traced the row entries back to the sys.seg$ table and successfully
deleted all deferred rollback entries (type#=2) on a test database. After
this step we were able to convert the system tablespace from DM to LM. I
doubt that this method is supported, but I am going back to Oracle to
discuss it further. In addition, the segment names within dba_segments
are named something like 1.24146. Is this a segment that we should be
able to find somewhere in the database? I am wondering if the sys.seg$
table was corrupt in that it may be referring to segments that don't
actually exist. Ok, I am going back in for some more. Please let me
know your thoughts. Thanks
Tracy Rahmlow_at_AMEX
Sent by: oracle-l-bounce_at_freelists.org
05/11/2004 10:05 AM
Please respond to oracle-l
To: oracle-l_at_freelists.org
cc:
Subject: Deferred Rollback Segments - Help!
We have upgraded from 8.1.7.4 to 9.2.0.5 on AIX 5.1 and converted to
automated undo. All tablespaces are locally managed except for system.
During the conversion of the system tablespace from DMT to LMT we receive
an ORA-03113. We have filed a TAR and Oracle states that we have deferred
rollback segments that were never applied or never removed after
application. (specifically to the user_data tablespace). All of our
tablespaces are online including user_data. Their solution is to create a
new database and import all the data to the new database due to the
"corruption". I have researched several other databases and we have an
additional 20+ databases with deferred rollback segments within the system
tablespace. (these databases do not have any offline tablespaces either)
Here is the query I ran:
select * from dba_extents where segment_type = 'DEFERRED ROLLBACK';
Has anyone experienced something similar? Any ideas on why we would have so many databases with this issue? I am not crazy about rebuilding 20+ databases. Is there a way to remove these segments? Here is Oracle's explanation which was included in the tar:
A "Deferred Rollback" segment is created for a tablespace when a tablespace is taken offline. Undo records are written to the deferred rollback segment of a tablespace when undo is being applied to a tablespace which is offline, hence, the undo cannot be applied.
The undo stored in the deferred rollback segment is applied when the tablespace comes back online. The deferred rollback segment is automatically removed after the undo has been applied.
Deferred rollback segments always reside in the system tablespace.
Please help! Thanks
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American Express made the following
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