1. Open a command console and go to the directory where you installed Postgre server.
e.g. D:\Program Files\PostgreSQL\9.3\bin>
2. Drill down into BIN folder and issue following command.
psql -d <database name> -U <username>
3. Issue CREATE EXTENSION command to import extension
CREATE EXTENSION "uuid-ossp" ;
NOTICE: There is a semicolon at the end of command.
4. After above steps, you can check if the extension has been imported successfully by calling following command.
select * from pg_extension;
5. If succeed, you should be able to see the list as below.
extname | extowner | extnamespace | extrelocatable | extversion | extconfig | extcondition
-----------+----------+--------------+----------------+------------+-----------+--------------
plpgsql | 10 | 11 | f | 1.0 | |
uuid-ossp | 89286 | 2200 | t | 1.0 | |
6. Now, you may generate UUID by uuid_generate_v4()
select uuid_generate_v4() ;