为自己加油

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.