UILD Utilities in PL/pgSQL

README.md

UILD for PL/pgSQL

ULID is a format for k-ordered distributed id generation. i.e. you can generate a random unique id with no central coordination and later be able to mostly sort the ids by the time they were generated.

When won't ids be sorted?

If ids are generated within the same second on different instances they could be out of order within that second.

Source of this code:

• Geckoboard Library
• Modfied Gist by kohenkatz

uild-text.sql

-- From https://github.com/geckoboard/pgulid/blob/d6187a00f66dca196cf5242588f87c3a7969df75/pgulid.sql
--
-- pgulid is based on OK Log's Go implementation of the ULID spec
--
-- 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 FUNCTION generate_ulid_text()
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);

  -- 10 entropy bytes
  ulid = timestamp || gen_random_bytes(10);

  -- 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)));

  -- Encode the entropy
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 6) & 248) >> 3));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 6) & 7) << 2) | ((GET_BYTE(ulid, 7) & 192) >> 6)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 7) & 62) >> 1));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 7) & 1) << 4) | ((GET_BYTE(ulid, 8) & 240) >> 4)));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 8) & 15) << 1) | ((GET_BYTE(ulid, 9) & 128) >> 7)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 9) & 124) >> 2));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 9) & 3) << 3) | ((GET_BYTE(ulid, 10) & 224) >> 5)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 10) & 31)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 11) & 248) >> 3));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 11) & 7) << 2) | ((GET_BYTE(ulid, 12) & 192) >> 6)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 12) & 62) >> 1));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 12) & 1) << 4) | ((GET_BYTE(ulid, 13) & 240) >> 4)));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 13) & 15) << 1) | ((GET_BYTE(ulid, 14) & 128) >> 7)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 14) & 124) >> 2));
  output = output || CHR(GET_BYTE(encoding, ((GET_BYTE(ulid, 14) & 3) << 3) | ((GET_BYTE(ulid, 15) & 224) >> 5)));
  output = output || CHR(GET_BYTE(encoding, (GET_BYTE(ulid, 15) & 31)));

  RETURN output;
END
$$
LANGUAGE plpgsql
VOLATILE;

ulid-parse-timestamp.sql

-- Gets the 48-bit time part of the ULID and returns a timestamp

CREATE FUNCTION ulid_to_timestamp(ulid UUID)
RETURNS TIMESTAMP WITH TIME ZONE
AS $$
  SELECT TO_TIMESTAMP(timepart::BIT(48)::BIGINT::DOUBLE PRECISION / 1000.0)
  FROM (
    SELECT ('x' || lpad((substring (u from 1 for 8) || substring (u from 10 for 4)), 12, '0')) AS timepart
    FROM (values (ulid::TEXT)) s (u)
  ) s;
$$
LANGUAGE sql
IMMUTABLE;

ulid-uuid.sql

-- Modified from https://github.com/geckoboard/pgulid/blob/d6187a00f66dca196cf5242588f87c3a7969df75/pgulid.sql
-- Returns a `uuid` type with the contents of the ULID
--
-- pgulid is based on OK Log's Go implementation of the ULID spec
--
-- 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 FUNCTION generate_ulid_uuid()
RETURNS UUID
AS $$
DECLARE
  timestamp  BYTEA = E'\\000\\000\\000\\000\\000\\000';

  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);

  -- 10 entropy bytes
  ulid = timestamp || gen_random_bytes(10);

  RETURN CAST( substring(CAST (ulid AS text) from 3) AS uuid);
END
$$
LANGUAGE plpgsql
VOLATILE;