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Oracle认证考试

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Examine the parameters for your database instance: Which three statements are true about the process of automatic optimization by using cardinality feedback?()

  • A、The optimizer automatically changes a plan during subsequent execution of a SQL statement if there is a huge difference in optimizer estimates and execution statistics.
  • B、The optimizer can re optimize a query only once using cardinality feedback.
  • C、The optimizer enables monitoring for cardinality feedback after the first execution of a query.
  • D、The optimizer does not monitor cardinality feedback if dynamic sampling and multicolumn statistics are enabled.
  • E、After the optimizer identifies a query as a re-optimization candidate, statistics collected by the collectors are submitted to the optimizer.
正确答案:A,C,D
答案解析:
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