正解:A,B,D
Keyword: shows the difference.
*Full ADDM analysis across two AWR snapshot periods
Detects causes, measure effects, then correlates them
Causes: workload changes, configuration changes
Effects: regressed SQL, reach resource limits (CPU, I/O, memory, interconnect) Makes actionable recommendations along with quantified impact *Identify what changed
/Configuration changes, workload changes
*Performance degradation of the database occurs when your database was performing optimally in the past, such as 6 months ago, but has gradually degraded to a point where it becomes noticeable to the users. The Automatic Workload Repository (AWR) Compare Periods report enables you to compare database performance between two periods of time.
While an AWR report shows AWR data between two snapshots (or two points in time), the AWR Compare Periods report shows the difference (ABE) between two periods (or two AWR reports with a total of four snapshots). Using the AWR Compare Periods report helps you to identify detailed performance attributes and configuration settings that differ between two time periods.