Data Warehouses and Data Mart

Because data can come from various sources, like OLTP, ERP, CRM, legacy applications, and external data sources, data can be stored in a diversified database, in different formats and structures. As a result, a data warehouse (DW), is the most important and expensive player in the whole BI system because it captures data from these diverse sources, and unifies them. The data is then ready to be accessed by BI system. As a central repository of business, DW contains data used for decision support systems (DSS) which focuses on the lower and middle management and makes it possible to look at and analyze data in different ways. Such data also used for executive information systems (EIS). Data extracted from the DW by departments are collected and put into smaller repository for easy and fast access are called data mart. Like data mart for marketing data, sales, production etc.