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Back to basics - Storage for a INT column that has NULL

  • December 1, 2004 at 3:44 pm

    #84944

    Gurus-

    I have a basic question.  If I have an INT column in a table that is nullable, and if I leave it NULL, will it still use 4 bytes?

    Appreciate your responses

  • December 1, 2004 at 7:31 pm

    #532129

    Yes

  • December 2, 2004 at 6:32 am

    #532176

    And that was a basic answer

  • December 2, 2004 at 9:07 am

    #532225

    Thanks guys

  • December 3, 2004 at 1:15 am

    #532352

    I might be wrong, ( i left my inside sql server 2000 book at work ) but I think if that is you only nullable column it will actually add 5 bytes to the row length.  If I remember correctly, sql server uses a bit array to store the nullability state of each column, but only if there are nullable columns.

     

    Ian Dundas
    Senior IT Analyst - Database
    Manitoba Public Insurance Corp.

  • December 3, 2004 at 3:05 am

    #532375

    Not exactly, the NULL bitmap is always there, even if no column allows for NULL.

     

    --
    Frank Kalis
    Microsoft SQL Server MVP
    Webmaster: http://www.insidesql.org/blogs
    My blog: http://www.insidesql.org/blogs/frankkalis/[/url]

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