Data Warehouse is needed for the following reasons:

1. Business User
2. Store historical data
3. Make strategic decisions
4. For data consistency and quality
5. High response time

1. Business User : Business users require a data warehouse to view summarised data from the past. Since these people are non-technical, the data may be presented to them in an elementary form.

2. Store historical data : Data Warehouse is required Io store the time variable data from the past. This input is made to be used for various purposes.

3. Make strategic decisions : Some strategies may be depending upon the data in the data warehouse. So, data warehouse contributes to making strategic decisions.

4. For data consistency and quality : Bringing the data from different sources at a commonplace, the user can effectively undertake to bring the uniformity and consistency in data.

5. High response time : Data warehouse has to he ready for somewhat unexpected loads and types of queries, which demands a significant degree of flexibility and quick response time.