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Oracle

1Z0-060 · Question #34

Which three features work together, to allow a SQL statement to have different cursors for the same statement based on different selectivity ranges?

The correct answer is A. Bind Variable Peeking C. Adaptive Cursor Sharing E. Literals in aSQL statement. *In bind variable peeking (also known as bind peeking), the optimizer looks at the value in a bind variable when the database performs a hard parse of a statement. When a query uses literals, the optimizer can use the literal values to find the best plan. However, when a query…

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Question

Which three features work together, to allow a SQL statement to have different cursors for the same statement based on different selectivity ranges?

Options

  • ABind Variable Peeking
  • BSQL Plan Baselines
  • CAdaptive Cursor Sharing
  • DBind variable used in a SQL statement
  • ELiterals in aSQL statement

How the community answered

(53 responses)
  • A
    75% (40)
  • B
    15% (8)
  • D
    9% (5)

Explanation

*In bind variable peeking (also known as bind peeking), the optimizer looks at the value in a bind variable when the database performs a hard parse of a statement. When a query uses literals, the optimizer can use the literal values to find the best plan. However, when a query uses bind variables, the optimizer must select the best plan without the presence of literals in the SQL text. This task can be extremely difficult. By peeking at bind values the optimizer can determine the selectivity of a WHERE clause condition as if literals had been used, thereby improving the plan. C:Oracle 11g/12guses Adaptive Cursor Sharing to solve this problem by allowing the server to compare the effectiveness of execution plans between executions with different bind variable values. If it notices suboptimal plans, it allows certain bind variable values, or ranges of values, to use alternate execution plans for the same statement. This functionality requires no additional

Topics

#adaptive cursor sharing#bind variable peeking#cursor selectivity#SQL plan management

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