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  1. #1
    Join Date
    May 2004

    Unanswered: purging data question

    I am purging data from few tables which my application uses. My question is what kind of impact does it have on my application if i do not rebuild the tables/indexes after the purge? Will there be a lot of gaps in the tables which would impact the perfomance of my application when runnint certain queries?

  2. #2
    Join Date
    Jan 2004
    Croatia, Europe
    Provided Answers: 5
    What do you cal "purging"? Delete? Truncate? Drop?

    Tables do not have to be rebuilt (unless you drop them); the same goes for indexes.

    Performance impact? Is high water mark what you have in mind? If so, depending on your definition of "purging" operation, you might consider use of the ALTER TABLE MOVE statement.

  3. #3
    Join Date
    May 2004
    I meant delete ( bulk delete)

    When you delete stuff out of tables it fills in the empty gaps in the memory pages which will impact the performance when doing the queries. Purpose of the rebuild is to remove those gaps.

  4. #4
    Join Date
    Aug 2003
    Where the Surf Meets the Turf @Del Mar, CA
    Provided Answers: 1
    >it fills in the empty gaps in the memory pages which will impact the performance when doing the queries.

    Please post reproducible benchmark test that quantifies & substantiates the statement above.

    By exactly how much are queries impacted by these "gaps"?
    What are the actual costs to eliminate the gaps?

    Do results differ between dictionary managed tablespaces & locally managed tablespaces?

    My advice, is to stop thinking about these gaps & instead worry whether the sun will rise tomorrow & from which direction it will rise.

    It is more important that the table (& indexes) have current statistics.
    Last edited by anacedent; 12-05-08 at 15:51.
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