Results 1 to 5 of 5
  1. #1
    Join Date
    Mar 2002
    Location
    Ireland
    Posts
    181

    Unanswered: question on indexes

    Hi,
    I have a composite index already on columns a, b and c on a table.
    Does it make sense to create another index just on column c or will any query (in theory) of the form .... where c = xx
    use the existing composite index ?
    Thanks for any help.
    Rgs,
    Breen.

  2. #2
    Join Date
    Mar 2002
    Location
    Ireland
    Posts
    181
    Just been looking around and it looks like it probably won't as c is not the leading edge of the existing index.

    Ahhh nuts.

    Rgs,
    Breen.

  3. #3
    Join Date
    Sep 2002
    Location
    UK
    Posts
    5,171
    Provided Answers: 1
    Yes. Actually, the index could be used via an index skip scan, but that is nowhere near as good as an index range scan and so likely will not happen in many cases.

  4. #4
    Join Date
    Jul 2003
    Posts
    2,296
    investigate creating a bitmap index on column c
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  5. #5
    Join Date
    Apr 2003
    Location
    Greenville, SC (USA)
    Posts
    1,155
    Or does it make sense to have a reverse key index ???

    Gregg

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •