The v$session_event view does not report in real time. In fact, the information could be as old as 3 seconds! Even though it has a column named time_waited_micro, the contents could have been updated seconds ago. So don't be fooled. If you want real-time details, you will need to sample from the v$session_wait view. The only significant difference between the system event view columns, listed in Table 2-1, and the session event view column is the session identifier column (sid) in the latter.

Figure 2-9 is a report based on v$session_event. Notice the command-line parameter is the session identifier. The report was run twice with around a 30-second gap. If session 205 were active, we would expect some increased wait-event activity. Notice that a couple of the wait times did increase. We would never expect the wait time to decrease unless session 205 disconnected and then a new session 205 was initialized upon connection.

Figure 2-9. Based on the session level view, v$session_event, this report allows session-level wait time questions to be answered. Two snapshots are shown to demonstrate how as the session continues to be connected, its wait time can increase.