A relation or relational attribute is an attribute containing as values the ordinal number of the elements of another domain. It thereby defines a mapping from each element of the domain for which it is an attribute to that other domain-unit. The following picture illustrates this:

A relation has the source domain as domain unit and the related/target domain as values-unit. It’s a mapping from the source towards the elated/target domain.

Synonyms in use for relation: partitioning, index-attribute, relational attribute;

naming convention

It is advised to use the postfix _rel when naming index attributes, see also naming-conventions.

how to make

Relations are often made with a rlookup or point_in_polygon function. See also relational-attribute-example.


Relations are often used in relational-functions and aggregation-functions.