ULID PL/pgSQL

ulid.sql

CREATE EXTENSION IF NOT EXISTS pgcrypto;

CREATE OR REPLACE FUNCTION uuid_generate_ulid ()
  RETURNS uuid
  AS $$
DECLARE
  timestamp bytea = E'\\000\\000\\000\\000\\000\\000';
  unix_time bigint;
BEGIN
  unix_time = (EXTRACT(EPOCH FROM clock_timestamp()) * 1000)::bigint;
  timestamp = SET_BYTE(timestamp, 0, (unix_time >> 40)::bit(8)::integer);
  timestamp = SET_BYTE(timestamp, 1, (unix_time >> 32)::bit(8)::integer);
  timestamp = SET_BYTE(timestamp, 2, (unix_time >> 24)::bit(8)::integer);
  timestamp = SET_BYTE(timestamp, 3, (unix_time >> 16)::bit(8)::integer);
  timestamp = SET_BYTE(timestamp, 4, (unix_time >> 8)::bit(8)::integer);
  timestamp = SET_BYTE(timestamp, 5, unix_time::bit(8)::integer);
  RETURN encode(timestamp || gen_random_bytes(10), 'hex')::uuid;
END
$$
LANGUAGE plpgsql
VOLATILE;