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pgulid.sql
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pgulid.sql
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-- 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 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);
-- 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;