index rebuild can screw app??
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Thread: index rebuild can screw app??

  1. #1
    Join Date
    Nov 2000
    Posts
    416
    Is it possible the alter index rebuild make the application too slow? After this command do we need to do analyze index? I guess
    all stat for CBO will gone after this command? what's happened?
    An ounce of prevention is worth a pound of cure

  2. #2
    Join Date
    Sep 2000
    Posts
    96
    Rebuild index should make app run better, if anything. This would be because the rebuild re-organizes the index....removed deleted leafs, etc. It probably wouldn't hurt to analyze after a rebuild, but I don't think it's a must.

  3. #3
    Join Date
    Feb 2001
    Posts
    290
    Analyzing index will infact improve the performance and I do analyze of some of the schemas in my database every day .

    My options are :
    estimate , 15%

    I use DBMS_UTILITY.ANALYZE_SCHEME

    rebuilding indexes is not a daily activity , but analyzing should be a daily one in order to provide a right feed to CBO to improve performance.

    Thanks,
    Madhu

  4. #4
    Join Date
    Nov 2000
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    greenwich.ct.us
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    9,095
    Originally posted by mrvajrala
    but analyzing should be a daily one in order to provide a right feed to CBO to improve performance.
    Depends on how often the characteristics of your data changes.

    I was once at a site where they had about 3 years of historical data. They loaded several million rows a day, but that didn't change the characteristics of the data. They computed statistics once every 6 months.
    Jeff Hunter
    marist89@yahoo.com
    http://marist89.blogspot.com/
    Get Firefox!
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  5. #5
    Join Date
    Nov 2000
    Posts
    416
    Guys, what's happened in my case was after I rebuild the index the application get slow significantly ( from other floors folks called me immediately and I paniced !! ) then I search google and find out someboy said do analyze tabel ... for all indexes and I did that and BOOM ... application get back to normal speed , no more complains I recieved. NOWHERE in Oracle Doc this is mention. Do you know why?? i really paniced!
    An ounce of prevention is worth a pound of cure

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