interview Question: Wait Events

 1.) wait event related to wrong password?
      "failed long delay",  'Library cache lock' or 'row cache lock' can be observed when concurrent users         login with wrong password to the database. The 'row cache lock' is seen in 10.2 and 11.1 while the         'library cache lock' is seen in 11.2.

2.) if you run a procedure ( infinite loop) in one session,and try to compile and modify ,which wait event you may see?
      if you try and compile infinite_loop in another session,it'll hand,stuck on "Library cache pin";
      if ,yet in another session,you try and created a modified version of it,it'll hand on "library cahch lock".

3.) How Library cache lock and pins are handled in RAC?
       things are different in RAC. Library cache lock and pins are global resources and controlled by GES           layer .