Snapshot too old while doing Export
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Thread: Snapshot too old while doing Export

  1. #1
    Join Date
    Mar 2001
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    New York , New York
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    577
    Hi,
    I am trying to do a full database export but am getting the following error

    EXP-00008: ORACLE error 1555 encountered
    ORA-01555: snapshot too old: rollback segment number 8 with name "RB5" too small

    EXP-00000: Export terminated unsuccessfully

    Please suggest

    Ronnie




  2. #2
    Join Date
    Nov 2000
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    greenwich.ct.us
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    Your rollback segments are too small. Search for 1555 in these forums for explanations...
    Jeff Hunter
    marist89@yahoo.com
    http://marist89.blogspot.com/
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    "I pledge to stop eating sharks fin soup and will not do so under any circumstances."

  3. #3
    Join Date
    Jul 2000
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    521
    Rollback segment size is not the primary reason for this error.

    Basic reason is, the tables that you are trying to export are getting changed (UPD/INs/DEL) while the export is on. And ORACLE's attempt to get a read consistent copy of a table is failing.

    Sure solution for this is : Stop those changes happening during exports.
    svk

  4. #4
    Join Date
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    Originally posted by svk
    Rollback segment size is not the primary reason for this error.
    No, the ONLY reason why you get this error is because your rollback segments are too small.

    The frequent changes to your data are exaggerating this condition, but the underlying problem is your RBS are too small!
    Jeff Hunter
    marist89@yahoo.com
    http://marist89.blogspot.com/
    Get Firefox!
    "I pledge to stop eating sharks fin soup and will not do so under any circumstances."

  5. #5
    Join Date
    Jul 2000
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    521
    Its very easy to simulate this error.

    If I know what kind of operations are happening, I can demonstrate this error irrespective of rollback segment size and number of rollback segments.

    ORA-1555 is probably the most discussed oracle error on the Net. You can find it at quite a few places that ORACLE's error message for this number is mis-leading.

    Its also known that howsoever huge rollbacks you create, you can not gurantee that this error will not occur during export if data changes are happening simultaneously.
    svk

  6. #6
    Join Date
    Sep 2001
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    NJ, USA
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    In my mind the problem not in size of rollback segment(s),
    most probability, problem in not enougth RBS for new transaction during export.
    Oracle use READ ONLY transactions in exp utility, and all RBS for uncommited and commited trasactions should be store all(or part) export time. If doesn't exists free RBS for new transaction, oracle generate error ORA-1555.

    Problem in number :
    #RBS(online) * TRANSACTION_PER_ROLLBACK_SEGMENT (init.ora)

    and summary number transaction during export process.

  7. #7
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
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    You are getting ORA-1555, because Oracle cannot create a read consistent picture of the table. Getting the ORA-1555 on an export with 'consistent=Y' is common. Are you making a consistent export?

    A rollback segment will not extend to preserve read consistent information for the export. Make the export when other people are not accessing the DB.




  8. #8
    Join Date
    Oct 2001
    Posts
    9
    well the main problem is the rollback segment is too small...you can increase the size of them next time...but on the interim solution you can bring the rollback segment that is full offline and the next available rollback segment will take over and complete your export....but afterward try to increase your rollback segment.....

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