From f53c76291c2b832aab9bcac0dd96b05ad37c37cd Mon Sep 17 00:00:00 2001 From: "Andrey M. Borodin" Date: Sun, 20 Aug 2023 23:55:31 +0300 Subject: [PATCH v4] Implement UUID v7 as per IETF draft Authors: Andrey Borodin, Sergey Prokhorenko --- doc/src/sgml/func.sgml | 10 +++- src/backend/utils/adt/uuid.c | 76 ++++++++++++++++++++++++ src/include/catalog/pg_proc.dat | 3 + src/test/regress/expected/opr_sanity.out | 1 + src/test/regress/expected/uuid.out | 10 ++++ src/test/regress/sql/uuid.sql | 6 ++ 6 files changed, 105 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index be2f54c914..b2d89cf415 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -13947,13 +13947,21 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple gen_random_uuid + + gen_uuid_v7 + + - PostgreSQL includes one function to generate a UUID: + PostgreSQL includes three functions to generate a UUID: gen_random_uuid () uuid This function returns a version 4 (random) UUID. This is the most commonly used type of UUID and is appropriate for most applications. + +gen_uuid_v7 () uuid + + This function returns a version 7 (time-ordered + random) UUID. diff --git a/src/backend/utils/adt/uuid.c b/src/backend/utils/adt/uuid.c index 4f7aa768fd..fed0b1bc52 100644 --- a/src/backend/utils/adt/uuid.c +++ b/src/backend/utils/adt/uuid.c @@ -13,6 +13,9 @@ #include "postgres.h" +#include + +#include "access/xlog.h" #include "common/hashfn.h" #include "lib/hyperloglog.h" #include "libpq/pqformat.h" @@ -421,3 +424,76 @@ gen_random_uuid(PG_FUNCTION_ARGS) PG_RETURN_UUID_P(uuid); } + +static uint32_t sequence_counter; +static uint64_t previous_timestamp = 0; + + +Datum +gen_uuid_v7(PG_FUNCTION_ARGS) +{ + pg_uuid_t *uuid = palloc(UUID_LEN); + uint64_t tms; + struct timeval tp; + + gettimeofday(&tp, NULL); + + tms = ((uint64_t)tp.tv_sec) * 1000 + (tp.tv_usec) / 1000; + + tms = pg_hton64(tms<<16); + + /* Fill in time part */ + memcpy(&uuid->data[0], &tms, 6); + + if (tms == previous_timestamp) + { + /* Time did not change from the previous generation, we must increment counter */ + ++sequence_counter; + /* fill everything after the timestamp and counter with random bytes */ + if (!pg_strong_random(&uuid->data[8], UUID_LEN - 8)) + ereport(ERROR, + (errcode(ERRCODE_INTERNAL_ERROR), + errmsg("could not generate random values"))); + + /* most significant 4 bits of 18-bit counter */ + uuid->data[6] = (unsigned char)(sequence_counter >> 14); + /* next 8 bits */ + uuid->data[7] = (unsigned char)(sequence_counter >> 6); + /* least significant 6 bits */ + uuid->data[8] = (unsigned char)(sequence_counter); + } + else + { + /* fill everything after the timestamp with random bytes */ + if (!pg_strong_random(&uuid->data[6], UUID_LEN - 6)) + ereport(ERROR, + (errcode(ERRCODE_INTERNAL_ERROR), + errmsg("could not generate random values"))); + + /* + * Left-most counter bits are initialized as zero for the sole purpose + * of guarding against counter rollovers. + * See section "Fixed-Length Dedicated Counter Seeding" + * https://datatracker.ietf.org/doc/html/draft-ietf-uuidrev-rfc4122bis-09#monotonicity_counters + */ + uuid->data[6] = (uuid->data[6] & 0xf7); + + sequence_counter = ((uint32_t)uuid->data[8] & 0x3f) + + (((uint32_t)uuid->data[7]) << 6) + + (((uint32_t)uuid->data[6] & 0x0f) << 14); + + previous_timestamp = tms; + } + + /* + * Set magic numbers for a "version 7" (pseudorandom) UUID, see + * http://tools.ietf.org/html/rfc ??? + * https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format#name-creating-a-uuidv7-value + */ + /* set version field, top four bits are 0, 1, 1, 1 */ + uuid->data[6] = (uuid->data[6] & 0x0f) | 0x70; + /* set variant field, top two bits are 1, 0 */ + uuid->data[8] = (uuid->data[8] & 0x3f) | 0x80; + + PG_RETURN_UUID_P(uuid); +} diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 12fac15ceb..4e6089060a 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -9125,6 +9125,9 @@ { oid => '3432', descr => 'generate random UUID', proname => 'gen_random_uuid', proleakproof => 't', provolatile => 'v', prorettype => 'uuid', proargtypes => '', prosrc => 'gen_random_uuid' }, +{ oid => '3813', descr => 'generate UUID version 7', + proname => 'gen_uuid_v7', proleakproof => 't', provolatile => 'v', + prorettype => 'uuid', proargtypes => '', prosrc => 'gen_uuid_v7' }, # pg_lsn { oid => '3229', descr => 'I/O', diff --git a/src/test/regress/expected/opr_sanity.out b/src/test/regress/expected/opr_sanity.out index a1bdf2c0b5..3141183b01 100644 --- a/src/test/regress/expected/opr_sanity.out +++ b/src/test/regress/expected/opr_sanity.out @@ -857,6 +857,7 @@ sha384(bytea) sha512(bytea) gen_random_uuid() starts_with(text,text) +gen_uuid_v7() macaddr8_eq(macaddr8,macaddr8) macaddr8_lt(macaddr8,macaddr8) macaddr8_le(macaddr8,macaddr8) diff --git a/src/test/regress/expected/uuid.out b/src/test/regress/expected/uuid.out index 8e7f21910d..fc9f50e69e 100644 --- a/src/test/regress/expected/uuid.out +++ b/src/test/regress/expected/uuid.out @@ -168,5 +168,15 @@ SELECT count(DISTINCT guid_field) FROM guid1; 2 (1 row) +-- generation test for v7 +TRUNCATE guid1; +INSERT INTO guid1 (guid_field) VALUES (gen_uuid_v7()); +INSERT INTO guid1 (guid_field) VALUES (gen_uuid_v7()); +SELECT count(DISTINCT guid_field) FROM guid1; + count +------- + 2 +(1 row) + -- clean up DROP TABLE guid1, guid2 CASCADE; diff --git a/src/test/regress/sql/uuid.sql b/src/test/regress/sql/uuid.sql index 9a8f437c7d..02b8e7f10c 100644 --- a/src/test/regress/sql/uuid.sql +++ b/src/test/regress/sql/uuid.sql @@ -85,5 +85,11 @@ INSERT INTO guid1 (guid_field) VALUES (gen_random_uuid()); INSERT INTO guid1 (guid_field) VALUES (gen_random_uuid()); SELECT count(DISTINCT guid_field) FROM guid1; +-- generation test for v7 +TRUNCATE guid1; +INSERT INTO guid1 (guid_field) VALUES (gen_uuid_v7()); +INSERT INTO guid1 (guid_field) VALUES (gen_uuid_v7()); +SELECT count(DISTINCT guid_field) FROM guid1; + -- clean up DROP TABLE guid1, guid2 CASCADE; -- 2.37.1 (Apple Git-137.1)