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    unique constraint (XXX50.Z36_ID) in pc_server.log

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    • Article Type: General
    • Product: Aleph
    • Product Version: 20

    Problem Symptoms:
    Seeing many such error messages in pc_server.log:
    Oracle error: io_z36_write
    ORA-00001: unique constraint (XXX50.Z36_ID) violated

    Cause:
    Aleph GUI tries to perform a loan of an item that is already on loan. This is (properly) blocked by Oracle.

    Resolution:
    Z36_ID is a unique index on Z36_REC_KEY that contains the ADM-number plus item sequence.

    The message indicates that the system tries write a loan record for an item that already has a loan record. Of course this is not allowed. Usually such cases should already blocked by Aleph GUI and not by Oracle. Obviously GUI for any reason did not block this attempt in this single case.

    WE see in the logfile that there were exactly 1000 such messages during few seconds (there are 1000 error messages as Aleph tries 1000 times to write the Z36-record before it gives up). There were no other such messages before or after that.

    So the message does not indicate a general problem if it happens randomly. In any case there is no problem with the data consistency.

    Category: System Management (500)

    Subject: Oracle (500)

    • Article last edited: 10/8/2013