Conventional ADDM uses AWR which are based on reports taken during intervals.  Some changes will not appear on this conventional ADDM because changes where not great enough to trigger new AWR analysis.  This is also not a real-time comparison of performance.   ASH Active Session History is real-time and had the following characteristics:

1. Active Session History is a collection of real-time data stored in the SGA based on active session
2. Can be viewed via the V$ACTIVE_SESSION_HISTORY view.
3. EM Cloud has the ability to run ASH reports from:
   1. HOME PAGE à Performance Menu/Home à Logon with admin privilege à Under Average Active Sessions click ASH Reports à Enter Start and Stop time of report à click Generate.
4. Reports are placed under Run ASH Report Page.
5. ASH Reports are divided into the sections
   1. Top Events – top wait events
   2. Load Profile – Describes load during report period.
   3. Top SQL – order by amount of resource consumed by SQL statements.
   4. Top Sessions – order by sessions waiting for wait events.
   5. Top DB Objects/Files/Latches – order by top objects being used/accessed.
   6. Activity Over Time – Shows picks and values in performance over reporting period.
6. EM Cloud also includes new ASH Analytics page, providing graphical view of ASH data.

Larry Catt

OCP