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Thread: rollback segment and rbs tablespace

  1. #1
    Join Date
    Apr 2001
    Hi All,
    I am recreating all rollback segments for Oracle Currently, I have 20 PUBLIC rollback segments without OPTIMAL values and their size are different. I want to create them using storage as

    storage (
    initial 10M
    Next 10M
    Minextents 10
    optimal 100M

    Right now I have 3 G (1G x 3 datafile for RBS) for rollback. If I want to specify maxextents in my storage settings above, how to calculate it? 20 rollback * 100 M = 2 G. IF I don't specify maxextent, what kind of problem I may run into?

    Please advise!

  2. #2
    Join Date
    Apr 2000
    Edison, NJ
    There isn't quite a way to calculate the # maxextents. Typically, this is set to a high value. If you do not specify the # maxextents, then each of the rbs will end up having the default value, ie, the value of maxextents of the tablespace. If the ts or rbs value of the maxextents is low, and say a large transaction takes up the no. of maxextents defined (either for the rbs or the ts), the transaction would fail.

    [Edited by Halo on 10-03-2001 at 09:30 PM]

  3. #3
    Join Date
    Jun 2001
    Helsinki. Finland
    I think but I am not 100% sure the theoretical Oracle maxmum for MAXEXTENTS is 2147483645. Could be that this is the default.

  4. #4
    Join Date
    Oct 2000
    You are right about the max size , Julian. As for elintrend, you can loose about 2G of space if you don't size your maxextent.


  5. #5
    Join Date
    Oct 2001
    Buffalo, NY
    My take is you would want to prevent a maxextents error from occuring by setting it high - I usually set it to unlimited for rollbacks, and then manage the rb segs in other ways - by properly sizing them on creation with the transactions and monitoring the tablespace/datafiles via scripts or processes. If you tailor the maxextents to your 3G now, then at a later time get some more disk space for them, you could easily overlook readjusting the value and have it bite you when you don't expect it.
    Tim Hussar

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