Oracle 12c In-Memory option is an industry innovation by introducing dual format architecture which allows database objects to be stored in columnar format.  This brings significant performance improvement of SQL in both OLAP and mixed workload environments.  Key In-Memory terminologies such as dual-format SGA architecture, In-Memory components 1MB pool and 64KB pool and their functionalities will be introduced.  Actual case study from Walgreens will be presented with dramatic performance improvement on analytical SQLs. Testing results have been measured with various criteria to demonstrate the effects of In-Memory option. Major In-Memory operations and their benefit will be described in the SQL execution plans. Learned lessons and the observed advantages and disadvantages from the In-Memory option will be summarized at the end.