The extract, transform, and load (ETL) pattern proved very useful in different architectural solutions. In data warehousing, it is used even more often than in data migration.
A data warehouse is a large data store constructed from several data sources and is intended to be used for reporting and analysis purposes. Data warehouses are constantly updated by feeding data from the data sources.
A part of a data warehouse that focuses on a specific area of interest is called a data mart.
First systems using data aggregation in a single source were developed in the early 1970s. For example, AC Nielsen, a global marketing research firm, used what they called "data mart" around ...