Active Session History (ASH) analytics
ASH analytics is accessed by going to Performance | ASH Analytics. This feature is new in Enterprise Manager Cloud Control 12c and allows you to analyze the database performance across multiple dimensions. It is supported for any Oracle database Target of Version 10.2.0.4 or higher.
The information on this page comes entirely from the in-memory ASH samples that are captured per second, or from the disk data, which is one sample in every ten seconds. These ASH samples are active session information, and the corresponding session attributes are also captured; these become the performance dimensions on this page.
Each second of DB time is stored as one row in each sample. Different dimensions can be selected ...