True or False – Wait Events

March 31, 2010

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A continuation of the series of true or false quizzes for the week – maybe this one is too easy.  Today’s quiz is on the topic of wait events.   Assuming that the questions apply to a release of Oracle that has been available for up to five years, state why you believe that the answer to the question is true, or why you believe that the answer to the question is false.  Any answers that attempt to utilize logical fallacies will be scored as incorrect.

1. Assume that a database instance is being prepared for 1,500 to 2,000 sessions.  Given an unlimited budget, it is possible to configure the database instance to completely eliminate wait events.

2. Consider two identical Oracle databases with a single session connected to each database instance.  Each of the two sessions submits exactly the same SQL statement, with the first session experiencing no wait events while executing the query, and the second session experiencing nearly continuous I/O wait events.  The lack of wait events implies that the query execution for the first session is optimal, and should be the performance target for the second session.

3. Idle wait events are insignificant in performance tuning exercises, and should be ignored.

4. For every one minute of elapsed time, each CPU in the server is capable of accumulating 60 seconds of CPU wait time.

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Did I mention that I dislike true/false type questions?  But then these are not simple true/false questions.