There are several methods to monitor database performance, but EM is probably the most frequent used today.  Oracle Enterprise Manager Cloud Control is designed to manage the entire Oracle environment: database, server, middleware, and more.  OEM Cloud control requires additional licensing, however EM Express is provide free with Enterprise editions.

EM Express can be used to manage a single Oracle 12c database and it is actually built into the database.  EM Express is a light weight management console and provides basic administrative tasks with minimal impact to database operations.  EM Express has no background processes and it gathers information from already existing database stores.  The Performance Hub of Express provides the following abilities:

1. ASH Analytics.
2. SQL Monitor
3. ADDM
4. Workload metrics.
5. Resource usage
6. See real-time and historic data.
7. In historic mode AWR (Automatic Workload Repository) data is used.
8. Performance Hub tabs are
   1. Summary – real-time mode
   2. Activity – ASH analytics both real-time and historic.
   3. Workload – info about Top SQL
   4. RAC – RAC specific metrics.
   5. Monitor SQL – current and historic SQL executions.
   6. ADDM – ADDM reports both real-time and historic
   7. Current ADDM findings – performance analysis of last 5 minutes.

Larry Catt

OCP