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  1. #1
    Join Date
    Apr 2011

    Unanswered: Row format in db2

    I am just curious when a row format in a data page, change in db2.
    Because from the information center V9.7:

    A REORG-recommended operation has occurred when changes resulting from an ALTER TABLE statement affect the row format of the data. When this occurs, most subsequent operations on the table are restricted until a table
    reorganization operation completes successfully.

    Because when a drop column operation occurs on a table, a reorg reccomended operation is required, whereas when a add column operation occurs, a reorg recommended operation is not necessary. But I would think that when either on of the two(add column or drop column) operation occurs on a table, row format would change, and a reorg is necessary.

    But db2 puts the table in reorg pending state only when a drop column operation occurs or in some other scenarios when the data type of a column is changed. So in what way these operations are different from adding columns to a table scenario.

    Please help me understand this concept.
    Thanks for your help.

    I am using DB2 LUW V9.5,9.7.

  2. #2
    Join Date
    Jun 2003
    Toronto, Canada
    Provided Answers: 1
    A new column is added at the end of the row. Dropped or altered column can introduce changes in the middle of the row.

  3. #3
    Join Date
    Sep 2004
    Existing static SQL (from before the "add column") need not be redone since all its absolute addresses (on the phyisical row) are still valid. Even inserts and updates can still be done consistently (as long as they don't refer the new column, which is impossible with old static SQL).
    When bytes in the middle of the row change interpretation, the situation is of course different. Except for static SQL that only refers columns in front of the change. So, some packages will possibly not be invalidated. But the tablespace as a whole needs reorganisation before inserts or updates into it using the new row format are allowed.
    --_Peter Vanroose,
    __IBM Certified Database Administrator, DB2 9 for z/OS
    __IBM Certified Application Developer
    __ABIS Training and Consulting

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