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  1. #1
    Join Date
    Jul 2009
    Posts
    2

    Unanswered: Transaction rollbacks

    Hi all,

    I have observed certain 'transaction rollbacks' while running my app
    I collected these statistics from V$MYSTAT, V$STATNAME.

    1.user rollbacks
    2.transaction rollbacks
    3.rollback changes - undo records applied

    user rollbacks is always 0 (as far I understand, any rollbacks in app code or library(oci wrapper) would show up here). I don't understand why 'transaction rollback' happens! along with some value for 'rollback changes - undo records applied'. (e.g.: user rollbacks 0; transaction rollbacks 13; rollback changes - undo records applied 30) Further checks with the app has shown that this is happening during insertions. I commented out writing part of the app and then no 'transaction rollbacks' happen.

    Also I see that these statistics are of class (128, DEBUG). So is it something that application cannot avoid but should be done at oracle end?

    I would run this app in parallel batches.
    Could this statistic contribute to a high rollback per transaction ratio?
    Could this lead to performance issues?

    I tried generating 10046 trace on the session. But I couldn't find anything related to rollbacks in the trace file or tkprof output.

    Will putting a trigger on V$MYSTAT help to capture updates to the statistic value. In that case, is it possible to identify which insert(exact query) is causing the problem?

    Thanks in advance.

  2. #2
    Join Date
    Aug 2003
    Location
    Where the Surf Meets the Turf @Del Mar, CA
    Posts
    7,776
    Provided Answers: 1
    >this is happening during insertions.
    Please elaborate GREATLY.

    On which system is INSERT actually running?
    What is the source of the data being inserted?

    Is data going into DB on a row by row basis?
    Is data going into DB multiple rows from a single INSERT?

    Please post actual INSERT & EXPLAIN PLAN from it.
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