Autotrace
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Thread: Autotrace

  1. #1
    Join Date
    Mar 2002
    Posts
    301

    Autotrace

    I run autotrace on a select statement. I want to know what mean
    Cost, Card, Bytes in the output of the Autotrace.


    0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=14 Bytes=98)
    1 0 NESTED LOOPS (Cost=1 Card=14 Bytes=98)
    2 1 TABLE ACCESS (FULL) OF 'EMP' (Cost=1 Card=14 Bytes=70)
    3 1 INDEX (UNIQUE SCAN) OF 'PK_DEPT' (UNIQUE)


    Thank's
    Bensmail

  2. #2
    Join Date
    Feb 2001
    Location
    UAE
    Posts
    304
    Cost is the value selected by the optimizer. Optimizer selects the access path with the lowest cost value.

    Card is cardinality.

    Bytes specisfies the number of bytes accessed by the operation.
    Agasimani
    OCP(10g/9i/8i/8)

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