Difference between IOT, B-Tree and Bitmap index
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Thread: Difference between IOT, B-Tree and Bitmap index

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  1. #1
    Join Date
    Mar 2001
    Location
    New York , New York
    Posts
    577
    Hi,

    Whats the difference between an Index Oraganized table, a Table with a Btree Index and one with a bitmap Index.

    Under what circumstances should each be used ??

    Thanks

    Ronnie
    ronnie_yours@yahoo.com

    You can if you think you can.

  2. #2
    Join Date
    May 2002
    Posts
    2,645
    Article on IOT's:
    http://www.dbasupport.com/oracle/ora8/iot.shtml

    From Oracle8i DBA Bible by Gennick -

    B*Tree indexes:
    Good choice for most uses as they
    -maintain the sort order of the data, making it easy to look up range data
    -multicolumn indexes: you can use the leading edge columns to resolve a query, even if that query doesn't reference all columns in the index
    -they automatically stay balanced
    -performance remains relatively constant
    - can also specify reverse and unique

    Bitmapped indexes:
    -use them to index columns with that contain a relatively small number of distinct values
    -they are compact, saving space
    -were designed for query intensive databases, so not recommended for OLTP databases
    -not good for range scans
    -are available only in Enterprise Edition


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