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Thread: URGENT HELP!!!

  1. #1
    Join Date
    Aug 2000

    Hi all,
    I am facing some problem with the performance of the application.Yesterday,there a problem with an index,ie.Maxextent of an index was reached,So i dropped and recreated the index with a different storage clause.Now today we are facing that was application has become slow.Can anyone please let me know step by step process to speed up the application again.

    Vinod Kumar.

  2. #2
    Join Date
    Nov 2000



    Have you analyzed the index after re-creating it...? . If not please do a compute statistics for that.

    Hope it will solve your problem.


  3. #3
    Join Date
    Aug 2000
    hi aji,

    I have nt Analyzed the index after recreating it,but anyway i will do so using

    Analyze Index <Indx name>Compute statistics;

    Can u tell me what is the next step..of it.I know that this above statment will put some of the statistics in dba_indexes.Can u please tell me how to find out whether the index is ok or not.if it is not ok,then what should i do to solve it.


  4. #4
    Join Date
    Jul 2000
    Oxford, OH
    I concur, make sure that you analyze your index again.
    Also, if the column contains data that is highly skewed
    you'll need to create a histogram on the column. If
    the data is skewed and you don't have a histogram then
    Oracle will assume a flat distribution and the chances are
    it may not use the index or use it inappropriately.

    Just in case the syntax is...

    ANALYZE INDEX index_name compute statistics;

    you can also use estimate statistics sample # rows or
    sample # percent. The estimate is much faster and is
    usually sufficient as long as you give it enough data
    to get a good sampling. If you have a pretty uniform
    distribution then you can get away with a lower number.
    If you have a non-uniform distribution, then increase
    the number. If unsure, be safe and do a compute.

    To do a histogram if your column values are highly skewed:

    ANALYZE TABLE table_name compute statistics
    for columns column_names SIZE number of bands.
    Number of bands, from what I can gather is similar to
    number of buckets. The default is 75. If you have,
    say, 8 distinct values in the column then set bands =8.

    ANALYZE TABLE table_name compute statistics
    for columns column_names SIZE 8;

    Joe Ramsey
    Senior Database Administrator
    dbaDirect, Inc.

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