PLPGSQL Order ID Calculation

id.sql

-- needed for `gen_random_bytes`
CREATE EXTENSION IF NOT EXISTS pgcrypto;

/**
  Generate a unique Order ID based on current_timestamp, base32 and two bits of entropy.
  If two Orders are created at the exact same millisecond, we rely on the entropy to provide uniqueness.

  Usage:

  > select * from generate_order_id();
  generate_order_id
  -------------------
  01E43H2JAG

*/
CREATE OR REPLACE FUNCTION generate_order_id()
RETURNS TEXT
AS $$
DECLARE
  -- Crockford's Base32
  encoding   BYTEA = '0123456789ABCDEFGHJKMNPQRSTVWXYZ';
  timestamp  BYTEA = '\\000\\000\\000\\000\\000\\000';
  output     TEXT = '';
  unix_time  BIGINT;
  ulid       BYTEA;
BEGIN
  -- 6 timestamp bytes
  unix_time = (EXTRACT(EPOCH FROM current_timestamp) * 1000)::BIGINT;
  timestamp = SET_BYTE(timestamp, 0, (unix_time >> 40)::BIT(8)::INTEGER);
  timestamp = SET_BYTE(timestamp, 1, (unix_time >> 32)::BIT(8)::INTEGER);
  timestamp = SET_BYTE(timestamp, 2, (unix_time >> 24)::BIT(8)::INTEGER);
  timestamp = SET_BYTE(timestamp, 3, (unix_time >> 16)::BIT(8)::INTEGER);
  timestamp = SET_BYTE(timestamp, 4, (unix_time >> 8)::BIT(8)::INTEGER);
  timestamp = SET_BYTE(timestamp, 5, unix_time::BIT(8)::INTEGER);
  -- Entropy to make collisions rare
  ulid = timestamp || gen_random_bytes(2);
  -- Encode the timestamp
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 0) & 224) >> 5));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 0) & 31)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 1) & 248) >> 3));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 1) & 7) << 2) | ((GET_BYTE(ulid, 2) & 192) >> 6)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 2) & 62) >> 1));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 2) & 1) << 4) | ((GET_BYTE(ulid, 3) & 240) >> 4)));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 3) & 15) << 1) | ((GET_BYTE(ulid, 4) & 128) >> 7)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 4) & 124) >> 2));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 4) & 3) << 3) | ((GET_BYTE(ulid, 5) & 224) >> 5)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 5) & 31)));
  return output;
END
$$ LANGUAGE PLPGSQL;

id2.sql

-- Mostly based on pgulid, which is based on oklog, hence the license.
--
-- https://github.com/geckoboard/pgulid/blob/master/pgulid.sql
-- https://github.com/oklog/ulid
-- https://github.com/ulid/spec
--
-- Copyright 2016 The Oklog Authors
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.

CREATE EXTENSION IF NOT EXISTS pgcrypto;
CREATE SEQUENCE IF NOT EXISTS public.order_id_gen_seq;

SELECT * FROM generate_order_id();

CREATE OR REPLACE FUNCTION generate_order_id()
    RETURNS TEXT
AS $$
DECLARE
    -- Crockford's Base32
    encoding  BYTEA = '0123456789ABCDEFGHJKMNPQRSTVWXYZ';
    timestamp BYTEA = E'\\000\\000\\000\\000\\000\\000';
    output    TEXT  = '';
    unix_time BIGINT;
    ulid      BYTEA;
BEGIN
    -- 6 timestamp bytes
    unix_time = (EXTRACT(EPOCH FROM NOW()) * 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);
    ulid = timestamp;

    -- Encode the timestamp, this is a hand optimised unrolled loop that all the ULID masters use
    output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 0) & 224) >> 5));
    output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 0) & 31)));
    output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 1) & 248) >> 3));
    output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 1) & 7) << 2) | ((GET_BYTE(ulid, 2) & 192) >> 6)));
    output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 2) & 62) >> 1));
    output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 2) & 1) << 4) | ((GET_BYTE(ulid, 3) & 240) >> 4)));
    output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 3) & 15) << 1) | ((GET_BYTE(ulid, 4) & 128) >> 7)));
    output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 4) & 124) >> 2));
    output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 4) & 3) << 3) | ((GET_BYTE(ulid, 5) & 224) >> 5)));
    output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 5) & 31)));

    -- add value from sequence to prevent collisions
    output = output || nextval('order_id_gen_seq') % 99;
    RETURN output;
END;
$$
    LANGUAGE plpgsql
    VOLATILE;

01E43H2JAG still feels like a bit too long order ID ?