A data warehouse is an electronic system that gathers data from various sources within a company and uses the data to support management decision-making. As the below architecture diagram illustrates, traditional data warehouse architecture employs a three-tier structure composed of the following tiers: bottom tier, middle tier, and top tier. The bottom tier contains the database server used to extract data from many different sources. Middle Tier houses an OLAP server, transforming the data into a better-suited structure for analysis and complex querying. Meanwhile, the Top Tier is the client layer as it holds the tools used for high-level data analysis, querying reporting and data mining.
