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  1. #1
    Join Date
    Nov 2007
    Posts
    27

    Unanswered: Row Compression and NULL Values

    Hello,

    How does the ROW compression (Db2 LUW Ver 9 and above ) treats the NULL Values in columns? If there are 10-12 column with NULL values, will row compression consider this for compression?
    We can use value compression, but I guess we cannot use both value and row compression together?

    Thanks,
    Rajesh

  2. #2
    Join Date
    Jan 2003
    Posts
    4,292
    Provided Answers: 5
    They can be used together.

    Andy

  3. #3
    Join Date
    Sep 2003
    Posts
    237
    My understanding was that only nonnull fields are stored in a record on storage. After a few mb of these records(in 9.5) are inserted, in a table set for compression, a compression dictionary is built and subsequent records use tokens from the dictionary(if applicable). So null values do not enter the picture.
    mota

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