You notice that the performance of your production 24/7 Oracle 12c database has significantly degraded. Sometimes you are not able to connect to the instance because it hangs. You do not want to restart the database instance.
How can you detect the cause of the degraded performance?
A.Enable Memory Access Mode, which reads performance data from SGA. B.Use emergency monitoring to fetch data directly from SGA for analysis. C.Run Automatic Database Diagnostic Monitor (ADDM) to fetch information from the latest Automatic Workload Repository (AWR) snapshots. D.Use Active Session History (ASH) data and hang analysis in regular performance monitoring, E.Run ADDM in diagnostic mode.正确答案B
