Getting historical performance stats using Active Session History ASH dynamic views in Oracle 

Active Session History (ASH) is part of the Diagnostics and Tuning Pack. It samples information from the [G]V$ views allowing you to see current and historical information about active sessions on the database. They are loaded with lot of crucial data which you can utilize at the time of any issue or when you are doing advance troubleshooting.
Keep Watching & Learning!
My Blog : www.fatdba.com
GitHub: github.com/fatdba/Oracle-Data...