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  1. #1
    Join Date
    Nov 2007
    Posts
    27

    Unanswered: Index Use for a DPF Table

    Hello,

    I had a query regarding the use of indexes for a DPF table.
    Suppose I have a tableA which is distributed by columnA in a DPF environment. Now If i have a index on Column B and have a query with a filter on Column B. So I see that the db2 optimizer does not use the index on column b.
    So it necessary to have the distribution column in all the indexes for a DPF table ?

    Query: select * from tablea where columnB = <>;

    Thanks

    Rajesh

  2. #2
    Join Date
    Jan 2007
    Location
    Jena, Germany
    Posts
    2,721
    No, it is not necessary.

    The question is if you have statistics collected, how big the table is, etc. Maybe your table just has a few rows (on each partition) and going over an index is just slower than doing a table scan. Or maybe the predicate on column B has a very low selectivity so that the index won't help.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

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