* v$session_wait: This is real-time session level information. Starting in Oracle Database 10g, you can also get this information in v$session, which can be very useful and more efficient. The value of querying the real-time information is that you can see the lower-level parameters: p1, p2, and p3. These parameters contain very detailed information about the specific wait. For example, if the event is db file scattered read, p1 contains the first block's file number, p2 contains the block number, and p3 contains the number of blocks requested. However, for the event latch free, p2 contains the latch number, which can be cross-referenced in v$latchname.

A number of excellent white papers and books detail the wait event views, so there is no need to repeat that information here. But I will summarize the views with some actual sample script output to highlight important details.

You may also want to take a look at the v$event_name view, which lists all the wait events available for a specific Oracle release. It is also a great quick reference for the parameter values and the event classifications.