Current Active Session on a Oracle Table I'm running a query which updates an Oracle table through Datastage. The query is taking a long time to execute so I want to examine the query/session on that Oracle table in the database and determine how the query is being executed.   

Could someone please advise how I can examine that active query/session in DB? 

I'm using DB visualizer tool.
There's a feature of the Tuning Pack called Real Time SQL Monitoring. It's available in SQL Developer, OEM, or theoretically via some package calls - but you really want a GUI for this report. 



You can see each step of the plan as it executes and see what the wait events are. You'll also see right away if it's not running with the degree of parallelization that you're expecting.

Our resident database performance expert Maria Colgan has an excellent write-up on the topic here.