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  1. #1
    Join Date
    Jan 2012
    Posts
    14

    Question What is the benefit of extra levels of indirection when it comes to Secondary indices

    I was reading my database book textbook and am on a section about secondary and primary indices. It briefly mentions the idea of adding a second level of indirection between a secondary index and the file with the table. I don't get why anyone would do that.

    As you can see in the attached image, you could just as easily have the pointers on the far left point directly to the records in the file instead of going through an intermediate pointer. Under what scenario would this be helpful for the database? All I see is it adding another pointer hop.

    Attached Thumbnails Attached Thumbnails 2013-05-12 20.36.54.png  

  2. #2
    Join Date
    Feb 2004
    Location
    In front of the computer
    Posts
    15,579
    Review the difference between a pointer and a handle. Repost if you have specific questions.

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

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