Question on UNUSED Columns
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Thread: Question on UNUSED Columns

  1. #1
    Join Date
    Jul 2003
    Posts
    134

    Question on UNUSED Columns

    Could someone please answer this Q for me?

    Many Thanks,
    Vipassana

    ABC Company consolidated into one office building, so the very large EMPLOYEES table no longer requires the OFFICE_LOCATION column. The DBA decided to drop the column using the syntax below:
    ALTER TABLE hr.employees
    DROP COLUMN building_location
    CASCADE CONSTRAINTS;
    Dropping this column has turned out to be very time consuming and is requiring a large amount of undo space.
    What could the DBA have done to minimize the problem regarding time and undo space consumption?
    A. Use the Export and Import utilities to bypass undo.
    B. Mark the column as UNUSED.
    C. Remove the column at a later time when less activity is on the system.
    D. Drop all indexes and constraints associated with the column prior to dropping the column.
    E. Mark the column INVALID prior to beginning the drop to bypass undo.
    F. Remove the column using the DROP UNUSED COLUMNS command.

  2. #2
    Join Date
    Jun 2000
    Location
    Madrid, Spain
    Posts
    7,447
    RTFM

  3. #3
    Join Date
    Mar 2002
    Location
    Manchester, England
    Posts
    202
    I'll tell you what, you paint my house and I'll answer your exam questions

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