til/postgres/creating-custom-types.md

Creating Custom Types

PostgreSQL has support for creating custom types. When you need something more expressive than the built-in types and you don't want your data spread across multiple columns, you can instead create a custom type.

create type dimensions as (
  width integer,
  height integer,
  depth integer
);

This new type can then be used in the definition of a new table

create table moving_boxes (
  id serial primary key,
  dims dimensions not null
);

and when inserting data

insert into moving_boxes (dims) values (row(3,4,5)::dimensions);

See the create type docs for more details.