Performance related problem

Question

I have identified following problem in oracle.
I would like to explain it through an example for the understanding of exact problem
I created a view say ‘view_1’ and another view ‘view_2’ based on view ‘view_1’ there are some functions like sum involved in each view that’s why there was a need to make view on view … I kept on making views based on other views upto 5th level that is keeping the order my last view was view_5 that was based on view_4
Now when I run the query of view_5 I get the required result but when I query the last view e.g select * from view_5 the system goes into a very long wait state. I waited for more then 16 minutes but nothing happened so I had to cancel the query.
is there any limitation in oracle or how can i view statistics of and reasons of this wait state?
please help me

Answer 1

The biggest issue about the views that they are not designed for performance but for transperancy, easiness. Views can be of two types, mergeable and non-mergeable. Mostly, if the view is non-mergeable, its going to give a bad performance( not a strict rule though). So as you are using so many of them, there are chances that this thing is effecting you. Suggest you to post your query,its explain plan over here with full database version. Please use the { code } tag(without spaces) to do so.
HTH
Aman....