Oracle: interpreting Toad "Session Browser" data

It's composed by the following information:

• IO
• Waits
• Current Statement (explain plan)
• Open Cursor
• Access
• Locks
• RBS Usage
• Long Ops
• Statistics

I'm studying Waits and Current Statement Explain Plan. Locks and Long Ops are pretty intuitive, but which are the most im开发者_如何学编程portant factor that I should consider to monitor the execution on a Query?

This is a query example:

At the query level, you are generally interest in the event that has the highest Time Waited. However sometimes you have a query that runs quickly 99% of the time and badly 1% of the time. In that case the explain plan may give a clue as to why that might be the case.

At the session level, it depends WHY you are monitoring the sessions. You might be interested in ones related to long running transactions (potentially blocking other sessions), ones that are blocked, ones using more than a 'fair' share of CPU resources....