A data mart is a subset of a data warehouse that is designed to serve the specific needs of a single department or business line. It is a structure/access pattern specific to data warehouse environments, used to retrieve client-facing data. Data marts are usually oriented to a specific business line or team, and each department or business unit is considered the owner of its data mart, including all the hardware, software, and data. Data marts are designed to access large groups of related records and improve end-user response time by allowing users to have access to the specific type of data they need to view most often, by providing the data in a way that supports the collective view of a group of users.
Data marts are read-only, and while data warehouses are designed to be updated, data marts are not. Data marts are built from an existing data warehouse or other data sources through a complex procedure that involves multiple technologies and tools to design and construct a physical database, populate it with data, and set up intricate access and management protocols.
Data marts are subject-oriented relational databases that store transactional data in rows and columns, making it easy to access, organize, and understand. They contain historical data, and this structure makes it easier for an analyst to determine data trends. Data marts can be created from an existing data warehouse or from other sources, such as internal operational systems or external data.
Benefits of data marts include efficient access to a specific set of data for business intelligence, being an inexpensive alternative to developing an enterprise data warehouse, and providing summarized data that key stakeholders can use to quickly make informed decisions. Data marts also give employees highly granular access privileges, which means the company can authorize a certain person to view or retrieve specific data, helping companies to improve data governance and enforce information access policies.
