Just like human being uses brain to store all the required information, a computer application uses database for the storage purpose. Relational database management system plays a major role for online digital media, financial systems, insurance, health care, and transportation. The amount of data collected and analyzed in enterprises has increased several folds in volume, variety and velocity. Hence a continuous improvement process in Database management systems is inevitable. In this ongoing process, a new class of systems had been designed and implemented, giving rise to the new phenomenon of "Big Data". "Bigness" of Big Data, volume of data is only one factor in the requirements of modern data processing platforms Only homogeneous data can be processed in online transaction processing (OLTP) systems as it does not support heterogeneous and various formatted data. So we go for data warehouse and OLAP, here the detailed information can be stored in it. Data warehouse mainly used for structured data and some data shall be lost while retrieving data from different data sources. This problem has been overcome by big data. It can store terabytes of data and also unstructured format.