Database Reference
In-Depth Information
In Figure
9-6
, the administrator has switched from high-level summary performance information to detailed
performance information (not to be confused with ASH). This view can either display the foreground sessions only or
include background sessions. At times, having the ability to display only foreground or background wait information
is very valuable.
Figure 9-6.
The Average Active Sessions pane of the performance home page in EM12c, demonstrating an average
load involving both CPU and some I/O waits
■
When diagnosing performance issues, inspecting just the foreground sessions and then inspecting both
foreground and background sessions can help distinguish problems such as poor etl batch load design or an issue with
cursors not being closed correctly.
Tip
From the Average Active Sessions pane, you can quickly assess the performance statistics of the database.
By clicking one of the links at the bottom of the main page, you can access the Top Activity page to perform a more
detailed investigation.
Links can include the following:
•
Top Segments
•
Cluster Cache Coherency (in RAC)
•
Interconnects (in RAC)
•
Parallel Execution
•
Database Locks
•
SQL Monitoring
•
Top Consumers
•
Top Activity
•
Duplicate SQL
•
Instance Activity (in RAC)
Throughput
The Throughput tab shows throughput per second or per transaction. It has additional monitoring links to Top Consumers,
Duplicate SQL, Instance Locks, Instance Activity, and SQL Response Time. These tabs relink back to Top Activity,
locking pages, and information pages outside the Top Activity area.
