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1Z0-117 · Question #20

Examine the initialization parameters for a database an OLTP overload. What is the effect of changing the value of the parameter?

The correct answer is B. It influences the optimizer to use indexes instead of full table scans as the estimated cost of the using. OPTIMIZER_INDEX_COST_ADJ OPTIMIZER_INDEX_COST_ADJ lets you tune optimizer behavior for access path selection to be more or less index friendly--that is, to make the optimizer more or less prone to selecting an index access path over a full table scan. The default for this…

Understanding and Influencing the Optimizer

Question

Examine the initialization parameters for a database an OLTP overload. What is the effect of changing the value of the parameter?

Exhibit

1Z0-117 question #20 exhibit

Options

  • AIt influences the optimizer to always use the value of the parameter?
  • BIt influences the optimizer to use indexes instead of full table scans as the estimated cost of the using
  • CIt influences the optimizer to use full table scans instead of index scans as the estimated cost of full
  • DIt influenced the optimizer to use bitmap indexes as the estimated cost conversion from bimap is rowed

How the community answered

(15 responses)
  • A
    13% (2)
  • B
    80% (12)
  • C
    7% (1)

Explanation

OPTIMIZER_INDEX_COST_ADJ OPTIMIZER_INDEX_COST_ADJ lets you tune optimizer behavior for access path selection to be more or less index friendly--that is, to make the optimizer more or less prone to selecting an index access path over a full table scan. The default for this parameter is 100 percent, at which the optimizer evaluates index access paths at the regular cost. Any other value makes the optimizer evaluate the access path at that percentage of the regular cost. For example, a setting of 50 makes the index access path look half as expensive as normal.

Topics

#OPTIMIZER_INDEX_COST_ADJ#index cost#full table scan cost#optimizer parameters

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