SQL Queries To Analyze All Concurrent Requests

http://prabhatdshine.blogspot.in/2013/10/sql-queries-to-analyze-all-concurrent.html

-SYSTEMATIC APPROACH TO FINDOUT DETAILS ON LONG RUNNING REQUESTS-

Automatic Maintenance and Optimizer Statistic Collection managing with 12c and 11g

http://www.carajandb.com/en/blogs/blog-swinkler-en/180-automatic-maintenance-and-optimizer-statistic-collection-managing-with-12c-and-11g