Over the last 3 decades, organizations have built EDW that consolidates data from various sources across the organization to enable business decisions, typically, related to current operational metrics and future what-if analysis for strategy decisions.
The following figure shows you a typical EDW architecture and also shows how information flows from the various source systems to the hands of business users:
Let's take a look at the stack from bottom to top.
Typical data sources for an EDW are as follows:
OLTP databases: These databases store data for transactional systems such as customer relationship management (CRM), Enterprise resource planning (ERP), including manufacturing, inventory, shipping, and others.
XML and Text Files: Data is also received in the form of text files, which are generally delimited, or XML, or some other fixed format known within the organization.