Extensions, PostGIS, Full Text Search Dictionaries, Data Caching, and Tuning - Learning Heroku Postgres - page 186

UUID generation
It provides functions to generate universal unique identifiers (UUID). It is a special type of
identifier used in software applications to provide a reference number that is unique in any
context.
$ heroku pg:psql --app your-app-name
CREATE EXTENSION "uuid-ossp";
SELECT uuid_generate_v1();
uuid_generate_v1
--------------------------------------
d976c6de-af2e-11e4-b1fb-22000ae18ca6
For more information, visit the documentation at http://www.postgresql.org/docs/current/
static/uuid-ossp.html .