Profiling a session or a group of sessions is another term for session-level ORTA. There are a number of formatting possibilities, with every report writer claiming his is the best. Figure 2-18 shows just one option for this type of report. This format clearly supports ORTA from a high-level classification all the way down to the wait events and service time categories.

Session-level ORTA is useful when a very specific business-centric problem has been reported, and the underlying database interaction can be identified. Keep in mind that Oracle and operating systems are designed and built to share resources. This implies that any singularly transactional-focused report is the result of both the transaction under investigation and all the other activity. No Oracle session operates untouched by other Oracle sessions, because Oracle is built to share resources. Don't be fooled into thinking your session-level profile output is the result of only the processes run by the session being profiled.

There are times when a user's session can be uniquely identified by its session identifier and serial number. When this is possible, it is usually very easy to profile that session based solely on Oracle's performance views.