多项选择题 You work as a database administrator for Supportcenter.cn. Users in the SupportCenter PROD database complain about the slow response when accessing the database. In the Active Session Waiting： Configuration page you find that the majority of the wait time is for the redo log buffer. Further investigation using the Run Queue graph and operating system tools reveals that the redo log files are on the same disks， and that the disk I/O for the redo log files is the reason for the performance degradation.  Which two actions would you take to gain performance？（）

单项选择题 Initially，fortheAutomaticWorkloadRepository（AWR）statistics，theretentionperiodissetto7days，thecollectionintervalissetto30minutesandthecollectionlevelissettoTypicalinyourproductiondatabase.YouhavebeenusingtheMemoryAdvisorforthelastthreemonthstogeneraterecommendationsfortuningmemorycomponents.However，whenyouobservetheMemoryAdvisoronaFriday，youfindthatthestatisticsareavailableonlyfortwodays，ThursdayandFriday，ofthatweek.Whatwouldhavecausedthestatisticstoberemoved？（）

单项选择题 Inyourdatabaseserver，theparameterPLSQL_OPTIMIZE_LEVELhasbeensetto2.Whatwouldthissettingachieve？（）