Now-a-days, big data is hot term in IT. It contains large volume of data. This data may be structured, unstructured or semi structured. Each big data source has different characteristics like frequency, volume, velocity and veracity of the data. Reasons of growth in the volume are use of internet, smart phone, social networks, GPS devices and so on. However, analyzing big data is a very challenging problem today. Traditional data warehouse systems are not able to handle this large amount of data.