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  1. #1
    Join Date
    Nov 2003
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    5

    Question Unanswered: automatic space management

    do i have to rebuild index when i use automatic segment space management?
    Last edited by ccbr; 03-06-06 at 10:31.

  2. #2
    Join Date
    Jul 2003
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    2,296
    Do you mean do you EVER have to rebuild an index?
    POssibly, but unlikely.
    Only under unusual circumstances do indexes need rebuilding.
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  3. #3
    Join Date
    Nov 2003
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    5
    i know that i should first analyze the index and if wastage>%20 i should rebuild. what i meant is if my tablespace which contains indexes, is created with automatic segment space management is there need to rebuild the index or it automatically does it...
    i couldnt find something about this in the docs but our vendor told us "there is no need to rebuild because we use automatic space management"
    thanx

  4. #4
    Join Date
    May 2004
    Location
    Dominican Republic
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    721
    Probably because on ASM oracle uses uniform-sized extents whereas in DSM you can or not, reason *probably* segments could get fragmented and thus, in case of indexes, needing rebuild. But either way, the syntax you use to rebuild in DMS is the same syntax you use on ASM.

  5. #5
    Join Date
    Sep 2004
    Location
    London, UK
    Posts
    565
    Quote Originally Posted by ccbr
    i know that i should first analyze the index and if wastage>%20 i should rebuild.
    Does it say that anywhere in the documentation?

    The consensus seems to be that regular index rebuilds are a waste of time: for example see AskTom (also here) and Jonathan Lewis.

  6. #6
    Join Date
    Jul 2003
    Posts
    2,296
    I've only seen index rebuilds as helpful under extreme circumstances.
    Mostly if you are doing BULK inserts, updates, and deletes to a real-time table that is already getting inserts every second.

    A rebuild seemed to work in that situation.
    - The_Duck
    you can lead someone to something but they will never learn anything ...

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