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Thread: table scan

  1. #1
    Join Date
    Jan 2010
    Posts
    72

    Unanswered: table scan

    When there is no index created on table, optimizer uses table scan. What are the other scenarios optimizer uses table scan?

    Look forward to hear from you.

  2. #2
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    Quote Originally Posted by regtha View Post
    What are the other scenarios optimizer uses table scan?
    when the table does have indexes, but none of the indexes is useful for the execution plan
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  3. #3
    Join Date
    Apr 2008
    Location
    Iasi, Romania
    Posts
    561
    Provided Answers: 2
    when the table is so small, that an index scan it's an waste of time
    Florin Aparaschivei
    DB2 9.7, 10.5 on Windows
    Iasi, Romania

  4. #4
    Join Date
    Nov 2003
    Posts
    2,935
    Provided Answers: 12
    When more than approx. 30% of all rows are needed from the table

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