Cost-based optimization is not effective - Oracle Distributed Database concepts

Q.  If your distributed query contains ___________, then the cost-based optimization is not effective.
- Published on 04 Aug 15

a. Aggregates
b. Subqueries
c. Complex SQL
d. All mentioned above

ANSWER: All mentioned above
 

    Discussion

  • Nirja Shah   -Posted on 21 Sep 15
    - While cost-based optimization is performed transparently to the user, it is unable to improve the performance of several distributed query scenarios.

    - Specifically, if your distributed query contains any of the following, cost-based optimization is not effective:

    1. Aggregates

    2. Subqueries

    3. Complex SQL

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