Introduction to Denormalized Data Types

Extensibility

The main idea behind the PostgreSQL project from Michael Stonebraker has been extensibility. As a result of that design choice, some data types supported by PostgreSQL allow bypassing relational constraints. For instance, PostgreSQL supports arrays, which store several values in the same attribute value. In standard SQL, the content of the array would be completely opaque so that the array would be considered only as a whole.

The extensible design of PostgreSQL makes it possible to enrich the SQL language with new capabilities. Specific operators are built for denormalized data types and allow addressing values contained in an array or a JSON attribute value, integrating perfectly with SQL.

The following data types are built into PostgreSQL and extend its processing capabilities to another level.

• Arrays

• Composite types

• XML

• JSON

• Enum