text: CREATE EXTENSION IF NOT EXISTS pgcrypto;-- 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()
  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;
  