Guide to Data Warehousing and Business Intelligence
A Relational Database is a set of database tables that are related using keys from other database tables. A relational model can be "normalized" or "de-normalized. When a relational model is normalized, redundant data is removed from tables and additional tables are implemented.
Most operational applications today use relational databases. As a business evolves, columns can be added to tables and new tables can be added to the database. Relational databases are stable, flexible and work well for online transaction processing.
Due to the relatively high volume of tables, complex computer programs are needed to navigate the tables to obtain meaningful information. The need to "join" multiple tables can also create performance issues. Consequently, relational databases are often not ideal for online queries and for reporting, particularly when the volume of data in the database is large.
Most Data Warehousing applications, therefore, are built using dimensional models.