Introduction to Data Types

In a relational database, we deal with relations. The main property of a relation is that all the tuples that belong to a relation share a common data definition: they have the same list of attributes, and each attribute is of a specific data type. Then we might also have some more constraints.

Definition of relations in databases

“In relational database theory, a relation, as originally defined by E. F. Codd, is a set of tuples ($d_1$, $d_2$, …, $d_n$), where each element $d_j$ is a member of $D_j$, a data domain. Codd’s original definition notwithstanding, and contrary to the usual definition in mathematics, there is no ordering to the elements of the tuples of a relation. Instead, each element is termed an attribute value. An attribute is a name paired with a domain (nowadays, more commonly referred to as a type or data type). An attribute value is an attribute name paired with an element of that attribute’s domain, and a tuple is a set of attribute values in which no two distinct elements have the same name. Thus, in some accounts, a tuple is described as a function, mapping names to values.”

We’re going to see what data types PostgreSQL makes available to us as application developers and how to use them to enhance our application’s correctness, succinctness, and performance.