Stestakov ,
Your query shows me the present sorts , i ran it now and did see few rows , would you pl explain the columns

SORT,PROWS...

I could see some good hit ratios and negative values in sort column and sometimes 0, the other times a positive value ex: 100 ... what does that indicate ???

Pando,

do i need to bounce the database after adding the event in the init.ora , i have never added any events to init.ora file.

Thanks,
Madhu