diff options
Diffstat (limited to 'src/backend/utils/adt/uuid.c')
| -rw-r--r-- | src/backend/utils/adt/uuid.c | 34 |
1 files changed, 17 insertions, 17 deletions
diff --git a/src/backend/utils/adt/uuid.c b/src/backend/utils/adt/uuid.c index 4f8402ef925..be0f0f9f1ce 100644 --- a/src/backend/utils/adt/uuid.c +++ b/src/backend/utils/adt/uuid.c @@ -29,6 +29,7 @@ #define NS_PER_S INT64CONST(1000000000) #define NS_PER_MS INT64CONST(1000000) #define NS_PER_US INT64CONST(1000) +#define US_PER_MS INT64CONST(1000) /* * UUID version 7 uses 12 bits in "rand_a" to store 1/4096 (or 2^12) fractions of @@ -69,6 +70,7 @@ static bool uuid_abbrev_abort(int memtupcount, SortSupport ssup); static Datum uuid_abbrev_convert(Datum original, SortSupport ssup); static inline void uuid_set_version(pg_uuid_t *uuid, unsigned char version); static inline int64 get_real_time_ns_ascending(); +static pg_uuid_t *generate_uuidv7(uint64 unix_ts_ms, uint32 sub_ms); Datum uuid_in(PG_FUNCTION_ARGS) @@ -523,17 +525,17 @@ get_real_time_ns_ascending() * described in the RFC. This method utilizes 12 bits from the "rand_a" bits * to store a 1/4096 (or 2^12) fraction of sub-millisecond precision. * - * ns is a number of nanoseconds since start of the UNIX epoch. This value is + * unix_ts_ms is a number of milliseconds since start of the UNIX epoch, + * and sub_ms is a number of nanoseconds within millisecond. These values are * used for time-dependent bits of UUID. + * + * NB: all numbers here are unsigned, unix_ts_ms cannot be negative per RFC. */ static pg_uuid_t * -generate_uuidv7(int64 ns) +generate_uuidv7(uint64 unix_ts_ms, uint32 sub_ms) { pg_uuid_t *uuid = palloc(UUID_LEN); - int64 unix_ts_ms; - int32 increased_clock_precision; - - unix_ts_ms = ns / NS_PER_MS; + uint32 increased_clock_precision; /* Fill in time part */ uuid->data[0] = (unsigned char) (unix_ts_ms >> 40); @@ -547,7 +549,7 @@ generate_uuidv7(int64 ns) * sub-millisecond timestamp fraction (SUBMS_BITS bits, not * SUBMS_MINIMAL_STEP_BITS) */ - increased_clock_precision = ((ns % NS_PER_MS) * (1 << SUBMS_BITS)) / NS_PER_MS; + increased_clock_precision = (sub_ms * (1 << SUBMS_BITS)) / NS_PER_MS; /* Fill the increased clock precision to "rand_a" bits */ uuid->data[6] = (unsigned char) (increased_clock_precision >> 8); @@ -586,7 +588,8 @@ generate_uuidv7(int64 ns) Datum uuidv7(PG_FUNCTION_ARGS) { - pg_uuid_t *uuid = generate_uuidv7(get_real_time_ns_ascending()); + int64 ns = get_real_time_ns_ascending(); + pg_uuid_t *uuid = generate_uuidv7(ns / NS_PER_MS, ns % NS_PER_MS); PG_RETURN_UUID_P(uuid); } @@ -601,13 +604,13 @@ uuidv7_interval(PG_FUNCTION_ARGS) TimestampTz ts; pg_uuid_t *uuid; int64 ns = get_real_time_ns_ascending(); + int64 us; /* * Shift the current timestamp by the given interval. To calculate time * shift correctly, we convert the UNIX epoch to TimestampTz and use - * timestamptz_pl_interval(). Since this calculation is done with - * microsecond precision, we carry nanoseconds from original ns value to - * shifted ns value. + * timestamptz_pl_interval(). This calculation is done with microsecond + * precision. */ ts = (TimestampTz) (ns / NS_PER_US) - @@ -618,14 +621,11 @@ uuidv7_interval(PG_FUNCTION_ARGS) TimestampTzGetDatum(ts), IntervalPGetDatum(shift))); - /* - * Convert a TimestampTz value back to an UNIX epoch and back nanoseconds. - */ - ns = (ts + (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC) - * NS_PER_US + ns % NS_PER_US; + /* Convert a TimestampTz value back to an UNIX epoch timestamp */ + us = ts + (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC; /* Generate an UUIDv7 */ - uuid = generate_uuidv7(ns); + uuid = generate_uuidv7(us / US_PER_MS, (us % US_PER_MS) * NS_PER_US + ns % NS_PER_US); PG_RETURN_UUID_P(uuid); } |