PostgreSQL Better ID & UUID Generator

postgresql_id.sql

create schema shard_1;  
create sequence shard_1.global_id_sequence;

CREATE OR REPLACE FUNCTION shard_1.id_generator(OUT result bigint) AS $$  
DECLARE  
    our_epoch bigint := 1314220021721;
    seq_id bigint;
    now_millis bigint;
    -- the id of this DB shard, must be set for each
    -- schema shard you have - you could pass this as a parameter too
    shard_id int := 1;
BEGIN  
    SELECT nextval('shard_1.global_id_sequence') % 1024 INTO seq_id;

    SELECT FLOOR(EXTRACT(EPOCH FROM clock_timestamp()) * 1000) INTO now_millis;
    result := (now_millis - our_epoch) << 23;
    result := result | (shard_id << 10);
    result := result | (seq_id);
END
$$ LANGUAGE PLPGSQL;

select shard_1.id_generator();  

Output:
878162550749922330

Reference:
http://instagram-engineering.tumblr.com/post/10853187575/sharding-ids-at-instagram
http://rob.conery.io/2014/05/29/a-better-id-generator-for-postgresql/

postgresql_uuid.sql

ALTER USER root WITH superuser;

CREATE EXTENSION "uuid-ossp";

SELECT uuid_generate_v4();

SELECT LOWER(REPLACE(CAST(uuid_generate_v4() As varchar(50)), '-',''));

Output:
adf4ce7c-4892-42bf-a808-1ee96bf9a6b0
43b2ac4eb63f46e6bfe93fe6bbb6267d