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  1. #1
    Join Date
    Jan 2008
    Posts
    45

    Unanswered: APPEND mode and its impact

    Hi friends,

    I turned on the append mode on a table for improving mass inserts on that table.Does that impact select queries on that table later on??

    Also as far as i remember cluster index is not possible on a table with append mode.Does the append mode truly improve the insert performance?? If so by what extent


    Thanks

  2. #2
    Join Date
    Jan 2007
    Location
    Jena, Germany
    Posts
    2,721
    Yes, it does improve performance because DB2 will not spent any time in looking for free space on the pages but rather append the data right at the end. Naturally, this may cause more pages to be read at query time, which can have a negative performance impact.

    As for the "extent" of the impact, it depends - as usual.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  3. #3
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    Quote Originally Posted by db2rocks
    Hi friends,

    I turned on the append mode on a table for improving mass inserts on that table.Does that impact select queries on that table later on??

    Also as far as i remember cluster index is not possible on a table with append mode.Does the append mode truly improve the insert performance?? If so by what extent
    Thanks
    Just remember that with append, DB2 will not use empty space from rows that are deleted, it will always place new rows at the end of the table.

    The performance improvement is probably not significant, but why don't you test it?
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  4. #4
    Join Date
    Jan 2008
    Posts
    45
    I tested it and I did not see a great deal of improvement..Thanks all for your help

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