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Query about Rollback Segment [message #56363] Mon, 24 March 2003 23:07 Go to next message
purav
Messages: 7
Registered: August 2002
Junior Member
Hi,

I seem to be confused about the way Rollback segments function. How to have equally sized Rollback segments. Suppose the TableSpace for Rollback Seg is 500 MB and I have 5 Rollback segments RBS1, RBS2, RBS3, RBS4, RBS5. While creating each of them do I have to specify the size of each anywhere - I suppose NO. Then how do we say that all are equally sized ? Second query is can one transaction spread across (use) more than 1 RollBack Segment ?

Please help me clear my fundas!!

Regards,
Purav

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Re: Query about Rollback Segment [message #56367 is a reply to message #56363] Tue, 25 March 2003 05:21 Go to previous messageGo to next message
utsav
Messages: 94
Registered: March 2003
Member
Hey,

For the second part,One transaction can not spread over two rollback segments.

For the first part, i am not very sure, but u do specify the size of the roll back segments and i suppose the number of rol back segments.

I am looking into it and will answer u ASAP.

utsav.

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Re: Query about Rollback Segment [message #56375 is a reply to message #56363] Tue, 25 March 2003 15:30 Go to previous message
Anand
Messages: 161
Registered: August 1999
Senior Member
Hi,

Generally, rollback segs are created on a dedicated tablespace. Sizes of rollback segments are gauged by the STORAGE parameters specified during the creation of the rollback segs or the underlying tablespace. The STORAGE params you specify for the underlying tablespaces determines the storage specs for the rollback segs.

For eg.

CREATE TABLESPACE rollback
DATAFILE '/u01/oracle/data/rollback_1.dbf'
SIZE 500M REUSE
DEFAULT STORAGE(INITIAL 50M NEXT 25M MAXEXTENTS 256);

Once you specify the storage specs as above, you don't have to specify the storage params explicitly for the rollback segments. Just create :

CREATE ROLLBACK SEGMENT roll_1
TABLESPACE rollback;

If you don't specify storage params during the creation of the tablespace, you may have to specify it during the rollback segment creation.

That's it ! Hope your doubt is cleared !

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