Analysis prior to Big Data was done in a traditional Data Warehouse setup. Big Data has paved the way for analysis to be done in a more performant manner with a lot of flexibility. However, traditional data warehouses would still exist for a variety of reasons going forward and are not going away soon.
A Data Lake in your organization can augment and support the data warehouse in a variety of ways. A Data Warehouse can be used for a variety of easy canned report generations. The business can create these on the fly using the semantic data warehouse models on top of the transactional data model, which the transactional application deals with on a day to day basis.
Also, certain data warehouse requirements could very well be fulfilled by this Data Lake infrastructure and since they have huge historical data with them, it can be quite useful in many business...