Oracle OCP 1Z0 053 Q298(SQL Tuning Advisor&GATHER_STATS_JOB)

298.While tuning a SQL statement, the SQL Tuning Advisor finds an existing SQL profile for the statement
that has stale statistics available.
What would the optimizer do in this situation?
A. It updates the existing SQL profiles with current statistics.
B. It makes the statistics information available to GATHER_STATS_JOB.
C. It initiates the statistics collection process by running GATHER_STATS_JOB.
D. It logs a warning message in the alert log so that the DBA can perform statistics collection manually.
Answer: B

發現有過時的統計資訊時，SQL Tuning Advisor通過啟用一個作業去重新收集統計資訊

參考：http://blog.csdn.net/rlhua/article/details/14090013

Actions represent the jobs that are performed by a module. For example, the DBMS_SCHEDULER module can run the GATHER_STATS_JOB action to gather statistics on all database objects. If a single action is using the majority of the wait time, then you should investigate it.

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