Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * uuid.c
4 : * Functions for the built-in type "uuid".
5 : *
6 : * Copyright (c) 2007-2025, PostgreSQL Global Development Group
7 : *
8 : * IDENTIFICATION
9 : * src/backend/utils/adt/uuid.c
10 : *
11 : *-------------------------------------------------------------------------
12 : */
13 :
14 : #include "postgres.h"
15 :
16 : #include <limits.h>
17 : #include <time.h> /* for clock_gettime() */
18 :
19 : #include "common/hashfn.h"
20 : #include "lib/hyperloglog.h"
21 : #include "libpq/pqformat.h"
22 : #include "port/pg_bswap.h"
23 : #include "utils/fmgrprotos.h"
24 : #include "utils/guc.h"
25 : #include "utils/skipsupport.h"
26 : #include "utils/sortsupport.h"
27 : #include "utils/timestamp.h"
28 : #include "utils/uuid.h"
29 :
30 : /* helper macros */
31 : #define NS_PER_S INT64CONST(1000000000)
32 : #define NS_PER_MS INT64CONST(1000000)
33 : #define NS_PER_US INT64CONST(1000)
34 : #define US_PER_MS INT64CONST(1000)
35 :
36 : /*
37 : * UUID version 7 uses 12 bits in "rand_a" to store 1/4096 (or 2^12) fractions of
38 : * sub-millisecond. While most Unix-like platforms provide nanosecond-precision
39 : * timestamps, some systems only offer microsecond precision, limiting us to 10
40 : * bits of sub-millisecond information. For example, on macOS, real time is
41 : * truncated to microseconds. Additionally, MSVC uses the ported version of
42 : * gettimeofday() that returns microsecond precision.
43 : *
44 : * On systems with only 10 bits of sub-millisecond precision, we still use
45 : * 1/4096 parts of a millisecond, but fill lower 2 bits with random numbers
46 : * (see generate_uuidv7() for details).
47 : *
48 : * SUBMS_MINIMAL_STEP_NS defines the minimum number of nanoseconds that guarantees
49 : * an increase in the UUID's clock precision.
50 : */
51 : #if defined(__darwin__) || defined(_MSC_VER)
52 : #define SUBMS_MINIMAL_STEP_BITS 10
53 : #else
54 : #define SUBMS_MINIMAL_STEP_BITS 12
55 : #endif
56 : #define SUBMS_BITS 12
57 : #define SUBMS_MINIMAL_STEP_NS ((NS_PER_MS / (1 << SUBMS_MINIMAL_STEP_BITS)) + 1)
58 :
59 : /* sortsupport for uuid */
60 : typedef struct
61 : {
62 : int64 input_count; /* number of non-null values seen */
63 : bool estimating; /* true if estimating cardinality */
64 :
65 : hyperLogLogState abbr_card; /* cardinality estimator */
66 : } uuid_sortsupport_state;
67 :
68 : static void string_to_uuid(const char *source, pg_uuid_t *uuid, Node *escontext);
69 : static int uuid_internal_cmp(const pg_uuid_t *arg1, const pg_uuid_t *arg2);
70 : static int uuid_fast_cmp(Datum x, Datum y, SortSupport ssup);
71 : static bool uuid_abbrev_abort(int memtupcount, SortSupport ssup);
72 : static Datum uuid_abbrev_convert(Datum original, SortSupport ssup);
73 : static inline void uuid_set_version(pg_uuid_t *uuid, unsigned char version);
74 : static inline int64 get_real_time_ns_ascending();
75 : static pg_uuid_t *generate_uuidv7(uint64 unix_ts_ms, uint32 sub_ms);
76 :
77 : Datum
78 586320 : uuid_in(PG_FUNCTION_ARGS)
79 : {
80 586320 : char *uuid_str = PG_GETARG_CSTRING(0);
81 : pg_uuid_t *uuid;
82 :
83 586320 : uuid = (pg_uuid_t *) palloc(sizeof(*uuid));
84 586320 : string_to_uuid(uuid_str, uuid, fcinfo->context);
85 586284 : PG_RETURN_UUID_P(uuid);
86 : }
87 :
88 : Datum
89 5904 : uuid_out(PG_FUNCTION_ARGS)
90 : {
91 5904 : pg_uuid_t *uuid = PG_GETARG_UUID_P(0);
92 : static const char hex_chars[] = "0123456789abcdef";
93 : char *buf,
94 : *p;
95 : int i;
96 :
97 : /* counts for the four hyphens and the zero-terminator */
98 5904 : buf = palloc(2 * UUID_LEN + 5);
99 5904 : p = buf;
100 100368 : for (i = 0; i < UUID_LEN; i++)
101 : {
102 : int hi;
103 : int lo;
104 :
105 : /*
106 : * We print uuid values as a string of 8, 4, 4, 4, and then 12
107 : * hexadecimal characters, with each group is separated by a hyphen
108 : * ("-"). Therefore, add the hyphens at the appropriate places here.
109 : */
110 94464 : if (i == 4 || i == 6 || i == 8 || i == 10)
111 23616 : *p++ = '-';
112 :
113 94464 : hi = uuid->data[i] >> 4;
114 94464 : lo = uuid->data[i] & 0x0F;
115 :
116 94464 : *p++ = hex_chars[hi];
117 94464 : *p++ = hex_chars[lo];
118 : }
119 5904 : *p = '\0';
120 :
121 5904 : PG_RETURN_CSTRING(buf);
122 : }
123 :
124 : /*
125 : * We allow UUIDs as a series of 32 hexadecimal digits with an optional dash
126 : * after each group of 4 hexadecimal digits, and optionally surrounded by {}.
127 : * (The canonical format 8x-4x-4x-4x-12x, where "nx" means n hexadecimal
128 : * digits, is the only one used for output.)
129 : */
130 : static void
131 586320 : string_to_uuid(const char *source, pg_uuid_t *uuid, Node *escontext)
132 : {
133 586320 : const char *src = source;
134 586320 : bool braces = false;
135 : int i;
136 :
137 586320 : if (src[0] == '{')
138 : {
139 24 : src++;
140 24 : braces = true;
141 : }
142 :
143 9967026 : for (i = 0; i < UUID_LEN; i++)
144 : {
145 : char str_buf[3];
146 :
147 9380742 : if (src[0] == '\0' || src[1] == '\0')
148 36 : goto syntax_error;
149 9380730 : memcpy(str_buf, src, 2);
150 9380730 : if (!isxdigit((unsigned char) str_buf[0]) ||
151 9380718 : !isxdigit((unsigned char) str_buf[1]))
152 24 : goto syntax_error;
153 :
154 9380706 : str_buf[2] = '\0';
155 9380706 : uuid->data[i] = (unsigned char) strtoul(str_buf, NULL, 16);
156 9380706 : src += 2;
157 9380706 : if (src[0] == '-' && (i % 2) == 1 && i < UUID_LEN - 1)
158 1937034 : src++;
159 : }
160 :
161 586284 : if (braces)
162 : {
163 18 : if (*src != '}')
164 6 : goto syntax_error;
165 12 : src++;
166 : }
167 :
168 586278 : if (*src != '\0')
169 6 : goto syntax_error;
170 :
171 586272 : return;
172 :
173 48 : syntax_error:
174 48 : ereturn(escontext,,
175 : (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
176 : errmsg("invalid input syntax for type %s: \"%s\"",
177 : "uuid", source)));
178 : }
179 :
180 : Datum
181 0 : uuid_recv(PG_FUNCTION_ARGS)
182 : {
183 0 : StringInfo buffer = (StringInfo) PG_GETARG_POINTER(0);
184 : pg_uuid_t *uuid;
185 :
186 0 : uuid = (pg_uuid_t *) palloc(UUID_LEN);
187 0 : memcpy(uuid->data, pq_getmsgbytes(buffer, UUID_LEN), UUID_LEN);
188 0 : PG_RETURN_POINTER(uuid);
189 : }
190 :
191 : Datum
192 0 : uuid_send(PG_FUNCTION_ARGS)
193 : {
194 0 : pg_uuid_t *uuid = PG_GETARG_UUID_P(0);
195 : StringInfoData buffer;
196 :
197 0 : pq_begintypsend(&buffer);
198 0 : pq_sendbytes(&buffer, uuid->data, UUID_LEN);
199 0 : PG_RETURN_BYTEA_P(pq_endtypsend(&buffer));
200 : }
201 :
202 : /* internal uuid compare function */
203 : static int
204 41776958 : uuid_internal_cmp(const pg_uuid_t *arg1, const pg_uuid_t *arg2)
205 : {
206 41776958 : return memcmp(arg1->data, arg2->data, UUID_LEN);
207 : }
208 :
209 : Datum
210 82718 : uuid_lt(PG_FUNCTION_ARGS)
211 : {
212 82718 : pg_uuid_t *arg1 = PG_GETARG_UUID_P(0);
213 82718 : pg_uuid_t *arg2 = PG_GETARG_UUID_P(1);
214 :
215 82718 : PG_RETURN_BOOL(uuid_internal_cmp(arg1, arg2) < 0);
216 : }
217 :
218 : Datum
219 17046 : uuid_le(PG_FUNCTION_ARGS)
220 : {
221 17046 : pg_uuid_t *arg1 = PG_GETARG_UUID_P(0);
222 17046 : pg_uuid_t *arg2 = PG_GETARG_UUID_P(1);
223 :
224 17046 : PG_RETURN_BOOL(uuid_internal_cmp(arg1, arg2) <= 0);
225 : }
226 :
227 : Datum
228 154460 : uuid_eq(PG_FUNCTION_ARGS)
229 : {
230 154460 : pg_uuid_t *arg1 = PG_GETARG_UUID_P(0);
231 154460 : pg_uuid_t *arg2 = PG_GETARG_UUID_P(1);
232 :
233 154460 : PG_RETURN_BOOL(uuid_internal_cmp(arg1, arg2) == 0);
234 : }
235 :
236 : Datum
237 12742 : uuid_ge(PG_FUNCTION_ARGS)
238 : {
239 12742 : pg_uuid_t *arg1 = PG_GETARG_UUID_P(0);
240 12742 : pg_uuid_t *arg2 = PG_GETARG_UUID_P(1);
241 :
242 12742 : PG_RETURN_BOOL(uuid_internal_cmp(arg1, arg2) >= 0);
243 : }
244 :
245 : Datum
246 16290 : uuid_gt(PG_FUNCTION_ARGS)
247 : {
248 16290 : pg_uuid_t *arg1 = PG_GETARG_UUID_P(0);
249 16290 : pg_uuid_t *arg2 = PG_GETARG_UUID_P(1);
250 :
251 16290 : PG_RETURN_BOOL(uuid_internal_cmp(arg1, arg2) > 0);
252 : }
253 :
254 : Datum
255 18 : uuid_ne(PG_FUNCTION_ARGS)
256 : {
257 18 : pg_uuid_t *arg1 = PG_GETARG_UUID_P(0);
258 18 : pg_uuid_t *arg2 = PG_GETARG_UUID_P(1);
259 :
260 18 : PG_RETURN_BOOL(uuid_internal_cmp(arg1, arg2) != 0);
261 : }
262 :
263 : /* handler for btree index operator */
264 : Datum
265 9308 : uuid_cmp(PG_FUNCTION_ARGS)
266 : {
267 9308 : pg_uuid_t *arg1 = PG_GETARG_UUID_P(0);
268 9308 : pg_uuid_t *arg2 = PG_GETARG_UUID_P(1);
269 :
270 9308 : PG_RETURN_INT32(uuid_internal_cmp(arg1, arg2));
271 : }
272 :
273 : /*
274 : * Sort support strategy routine
275 : */
276 : Datum
277 388 : uuid_sortsupport(PG_FUNCTION_ARGS)
278 : {
279 388 : SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
280 :
281 388 : ssup->comparator = uuid_fast_cmp;
282 388 : ssup->ssup_extra = NULL;
283 :
284 388 : if (ssup->abbreviate)
285 : {
286 : uuid_sortsupport_state *uss;
287 : MemoryContext oldcontext;
288 :
289 308 : oldcontext = MemoryContextSwitchTo(ssup->ssup_cxt);
290 :
291 308 : uss = palloc(sizeof(uuid_sortsupport_state));
292 308 : uss->input_count = 0;
293 308 : uss->estimating = true;
294 308 : initHyperLogLog(&uss->abbr_card, 10);
295 :
296 308 : ssup->ssup_extra = uss;
297 :
298 308 : ssup->comparator = ssup_datum_unsigned_cmp;
299 308 : ssup->abbrev_converter = uuid_abbrev_convert;
300 308 : ssup->abbrev_abort = uuid_abbrev_abort;
301 308 : ssup->abbrev_full_comparator = uuid_fast_cmp;
302 :
303 308 : MemoryContextSwitchTo(oldcontext);
304 : }
305 :
306 388 : PG_RETURN_VOID();
307 : }
308 :
309 : /*
310 : * SortSupport comparison func
311 : */
312 : static int
313 41484376 : uuid_fast_cmp(Datum x, Datum y, SortSupport ssup)
314 : {
315 41484376 : pg_uuid_t *arg1 = DatumGetUUIDP(x);
316 41484376 : pg_uuid_t *arg2 = DatumGetUUIDP(y);
317 :
318 41484376 : return uuid_internal_cmp(arg1, arg2);
319 : }
320 :
321 : /*
322 : * Callback for estimating effectiveness of abbreviated key optimization.
323 : *
324 : * We pay no attention to the cardinality of the non-abbreviated data, because
325 : * there is no equality fast-path within authoritative uuid comparator.
326 : */
327 : static bool
328 2322 : uuid_abbrev_abort(int memtupcount, SortSupport ssup)
329 : {
330 2322 : uuid_sortsupport_state *uss = ssup->ssup_extra;
331 : double abbr_card;
332 :
333 2322 : if (memtupcount < 10000 || uss->input_count < 10000 || !uss->estimating)
334 2130 : return false;
335 :
336 192 : abbr_card = estimateHyperLogLog(&uss->abbr_card);
337 :
338 : /*
339 : * If we have >100k distinct values, then even if we were sorting many
340 : * billion rows we'd likely still break even, and the penalty of undoing
341 : * that many rows of abbrevs would probably not be worth it. Stop even
342 : * counting at that point.
343 : */
344 192 : if (abbr_card > 100000.0)
345 : {
346 0 : if (trace_sort)
347 0 : elog(LOG,
348 : "uuid_abbrev: estimation ends at cardinality %f"
349 : " after " INT64_FORMAT " values (%d rows)",
350 : abbr_card, uss->input_count, memtupcount);
351 0 : uss->estimating = false;
352 0 : return false;
353 : }
354 :
355 : /*
356 : * Target minimum cardinality is 1 per ~2k of non-null inputs. 0.5 row
357 : * fudge factor allows us to abort earlier on genuinely pathological data
358 : * where we've had exactly one abbreviated value in the first 2k
359 : * (non-null) rows.
360 : */
361 192 : if (abbr_card < uss->input_count / 2000.0 + 0.5)
362 : {
363 96 : if (trace_sort)
364 0 : elog(LOG,
365 : "uuid_abbrev: aborting abbreviation at cardinality %f"
366 : " below threshold %f after " INT64_FORMAT " values (%d rows)",
367 : abbr_card, uss->input_count / 2000.0 + 0.5, uss->input_count,
368 : memtupcount);
369 96 : return true;
370 : }
371 :
372 96 : if (trace_sort)
373 0 : elog(LOG,
374 : "uuid_abbrev: cardinality %f after " INT64_FORMAT
375 : " values (%d rows)", abbr_card, uss->input_count, memtupcount);
376 :
377 96 : return false;
378 : }
379 :
380 : /*
381 : * Conversion routine for sortsupport. Converts original uuid representation
382 : * to abbreviated key representation. Our encoding strategy is simple -- pack
383 : * the first `sizeof(Datum)` bytes of uuid data into a Datum (on little-endian
384 : * machines, the bytes are stored in reverse order), and treat it as an
385 : * unsigned integer.
386 : */
387 : static Datum
388 3384150 : uuid_abbrev_convert(Datum original, SortSupport ssup)
389 : {
390 3384150 : uuid_sortsupport_state *uss = ssup->ssup_extra;
391 3384150 : pg_uuid_t *authoritative = DatumGetUUIDP(original);
392 : Datum res;
393 :
394 3384150 : memcpy(&res, authoritative->data, sizeof(Datum));
395 3384150 : uss->input_count += 1;
396 :
397 3384150 : if (uss->estimating)
398 : {
399 : uint32 tmp;
400 :
401 3384150 : tmp = DatumGetUInt32(res) ^ (uint32) (DatumGetUInt64(res) >> 32);
402 :
403 3384150 : addHyperLogLog(&uss->abbr_card, DatumGetUInt32(hash_uint32(tmp)));
404 : }
405 :
406 : /*
407 : * Byteswap on little-endian machines.
408 : *
409 : * This is needed so that ssup_datum_unsigned_cmp() (an unsigned integer
410 : * 3-way comparator) works correctly on all platforms. If we didn't do
411 : * this, the comparator would have to call memcmp() with a pair of
412 : * pointers to the first byte of each abbreviated key, which is slower.
413 : */
414 3384150 : res = DatumBigEndianToNative(res);
415 :
416 3384150 : return res;
417 : }
418 :
419 : static Datum
420 0 : uuid_decrement(Relation rel, Datum existing, bool *underflow)
421 : {
422 : pg_uuid_t *uuid;
423 :
424 0 : uuid = (pg_uuid_t *) palloc(UUID_LEN);
425 0 : memcpy(uuid, DatumGetUUIDP(existing), UUID_LEN);
426 0 : for (int i = UUID_LEN - 1; i >= 0; i--)
427 : {
428 0 : if (uuid->data[i] > 0)
429 : {
430 0 : uuid->data[i]--;
431 0 : *underflow = false;
432 0 : return UUIDPGetDatum(uuid);
433 : }
434 0 : uuid->data[i] = UCHAR_MAX;
435 : }
436 :
437 0 : pfree(uuid); /* cannot leak memory */
438 :
439 : /* return value is undefined */
440 0 : *underflow = true;
441 0 : return (Datum) 0;
442 : }
443 :
444 : static Datum
445 0 : uuid_increment(Relation rel, Datum existing, bool *overflow)
446 : {
447 : pg_uuid_t *uuid;
448 :
449 0 : uuid = (pg_uuid_t *) palloc(UUID_LEN);
450 0 : memcpy(uuid, DatumGetUUIDP(existing), UUID_LEN);
451 0 : for (int i = UUID_LEN - 1; i >= 0; i--)
452 : {
453 0 : if (uuid->data[i] < UCHAR_MAX)
454 : {
455 0 : uuid->data[i]++;
456 0 : *overflow = false;
457 0 : return UUIDPGetDatum(uuid);
458 : }
459 0 : uuid->data[i] = 0;
460 : }
461 :
462 0 : pfree(uuid); /* cannot leak memory */
463 :
464 : /* return value is undefined */
465 0 : *overflow = true;
466 0 : return (Datum) 0;
467 : }
468 :
469 : Datum
470 0 : uuid_skipsupport(PG_FUNCTION_ARGS)
471 : {
472 0 : SkipSupport sksup = (SkipSupport) PG_GETARG_POINTER(0);
473 0 : pg_uuid_t *uuid_min = palloc(UUID_LEN);
474 0 : pg_uuid_t *uuid_max = palloc(UUID_LEN);
475 :
476 0 : memset(uuid_min->data, 0x00, UUID_LEN);
477 0 : memset(uuid_max->data, 0xFF, UUID_LEN);
478 :
479 0 : sksup->decrement = uuid_decrement;
480 0 : sksup->increment = uuid_increment;
481 0 : sksup->low_elem = UUIDPGetDatum(uuid_min);
482 0 : sksup->high_elem = UUIDPGetDatum(uuid_max);
483 :
484 0 : PG_RETURN_VOID();
485 : }
486 :
487 : /* hash index support */
488 : Datum
489 2426 : uuid_hash(PG_FUNCTION_ARGS)
490 : {
491 2426 : pg_uuid_t *key = PG_GETARG_UUID_P(0);
492 :
493 2426 : return hash_any(key->data, UUID_LEN);
494 : }
495 :
496 : Datum
497 60 : uuid_hash_extended(PG_FUNCTION_ARGS)
498 : {
499 60 : pg_uuid_t *key = PG_GETARG_UUID_P(0);
500 :
501 60 : return hash_any_extended(key->data, UUID_LEN, PG_GETARG_INT64(1));
502 : }
503 :
504 : /*
505 : * Set the given UUID version and the variant bits
506 : */
507 : static inline void
508 53640 : uuid_set_version(pg_uuid_t *uuid, unsigned char version)
509 : {
510 : /* set version field, top four bits */
511 53640 : uuid->data[6] = (uuid->data[6] & 0x0f) | (version << 4);
512 :
513 : /* set variant field, top two bits are 1, 0 */
514 53640 : uuid->data[8] = (uuid->data[8] & 0x3f) | 0x80;
515 53640 : }
516 :
517 : /*
518 : * Generate UUID version 4.
519 : *
520 : * All UUID bytes are filled with strong random numbers except version and
521 : * variant bits.
522 : */
523 : Datum
524 42 : gen_random_uuid(PG_FUNCTION_ARGS)
525 : {
526 42 : pg_uuid_t *uuid = palloc(UUID_LEN);
527 :
528 42 : if (!pg_strong_random(uuid, UUID_LEN))
529 0 : ereport(ERROR,
530 : (errcode(ERRCODE_INTERNAL_ERROR),
531 : errmsg("could not generate random values")));
532 :
533 : /*
534 : * Set magic numbers for a "version 4" (pseudorandom) UUID and variant,
535 : * see https://datatracker.ietf.org/doc/html/rfc9562#name-uuid-version-4
536 : */
537 42 : uuid_set_version(uuid, 4);
538 :
539 42 : PG_RETURN_UUID_P(uuid);
540 : }
541 :
542 : /*
543 : * Get the current timestamp with nanosecond precision for UUID generation.
544 : * The returned timestamp is ensured to be at least SUBMS_MINIMAL_STEP greater
545 : * than the previous returned timestamp (on this backend).
546 : */
547 : static inline int64
548 53598 : get_real_time_ns_ascending()
549 : {
550 : static int64 previous_ns = 0;
551 : int64 ns;
552 :
553 : /* Get the current real timestamp */
554 :
555 : #ifdef _MSC_VER
556 : struct timeval tmp;
557 :
558 : gettimeofday(&tmp, NULL);
559 : ns = tmp.tv_sec * NS_PER_S + tmp.tv_usec * NS_PER_US;
560 : #else
561 : struct timespec tmp;
562 :
563 : /*
564 : * We don't use gettimeofday(), instead use clock_gettime() with
565 : * CLOCK_REALTIME where available in order to get a high-precision
566 : * (nanoseconds) real timestamp.
567 : *
568 : * Note while a timestamp returned by clock_gettime() with CLOCK_REALTIME
569 : * is nanosecond-precision on most Unix-like platforms, on some platforms
570 : * such as macOS it's restricted to microsecond-precision.
571 : */
572 53598 : clock_gettime(CLOCK_REALTIME, &tmp);
573 53598 : ns = tmp.tv_sec * NS_PER_S + tmp.tv_nsec;
574 : #endif
575 :
576 : /* Guarantee the minimal step advancement of the timestamp */
577 53598 : if (previous_ns + SUBMS_MINIMAL_STEP_NS >= ns)
578 0 : ns = previous_ns + SUBMS_MINIMAL_STEP_NS;
579 53598 : previous_ns = ns;
580 :
581 53598 : return ns;
582 : }
583 :
584 : /*
585 : * Generate UUID version 7 per RFC 9562, with the given timestamp.
586 : *
587 : * UUID version 7 consists of a Unix timestamp in milliseconds (48 bits) and
588 : * 74 random bits, excluding the required version and variant bits. To ensure
589 : * monotonicity in scenarios of high-frequency UUID generation, we employ the
590 : * method "Replace Leftmost Random Bits with Increased Clock Precision (Method 3)",
591 : * described in the RFC. This method utilizes 12 bits from the "rand_a" bits
592 : * to store a 1/4096 (or 2^12) fraction of sub-millisecond precision.
593 : *
594 : * unix_ts_ms is a number of milliseconds since start of the UNIX epoch,
595 : * and sub_ms is a number of nanoseconds within millisecond. These values are
596 : * used for time-dependent bits of UUID.
597 : *
598 : * NB: all numbers here are unsigned, unix_ts_ms cannot be negative per RFC.
599 : */
600 : static pg_uuid_t *
601 53598 : generate_uuidv7(uint64 unix_ts_ms, uint32 sub_ms)
602 : {
603 53598 : pg_uuid_t *uuid = palloc(UUID_LEN);
604 : uint32 increased_clock_precision;
605 :
606 : /* Fill in time part */
607 53598 : uuid->data[0] = (unsigned char) (unix_ts_ms >> 40);
608 53598 : uuid->data[1] = (unsigned char) (unix_ts_ms >> 32);
609 53598 : uuid->data[2] = (unsigned char) (unix_ts_ms >> 24);
610 53598 : uuid->data[3] = (unsigned char) (unix_ts_ms >> 16);
611 53598 : uuid->data[4] = (unsigned char) (unix_ts_ms >> 8);
612 53598 : uuid->data[5] = (unsigned char) unix_ts_ms;
613 :
614 : /*
615 : * sub-millisecond timestamp fraction (SUBMS_BITS bits, not
616 : * SUBMS_MINIMAL_STEP_BITS)
617 : */
618 53598 : increased_clock_precision = (sub_ms * (1 << SUBMS_BITS)) / NS_PER_MS;
619 :
620 : /* Fill the increased clock precision to "rand_a" bits */
621 53598 : uuid->data[6] = (unsigned char) (increased_clock_precision >> 8);
622 53598 : uuid->data[7] = (unsigned char) (increased_clock_precision);
623 :
624 : /* fill everything after the increased clock precision with random bytes */
625 53598 : if (!pg_strong_random(&uuid->data[8], UUID_LEN - 8))
626 0 : ereport(ERROR,
627 : (errcode(ERRCODE_INTERNAL_ERROR),
628 : errmsg("could not generate random values")));
629 :
630 : #if SUBMS_MINIMAL_STEP_BITS == 10
631 :
632 : /*
633 : * On systems that have only 10 bits of sub-ms precision, 2 least
634 : * significant are dependent on other time-specific bits, and they do not
635 : * contribute to uniqueness. To make these bit random we mix in two bits
636 : * from CSPRNG. SUBMS_MINIMAL_STEP is chosen so that we still guarantee
637 : * monotonicity despite altering these bits.
638 : */
639 : uuid->data[7] = uuid->data[7] ^ (uuid->data[8] >> 6);
640 : #endif
641 :
642 : /*
643 : * Set magic numbers for a "version 7" (pseudorandom) UUID and variant,
644 : * see https://www.rfc-editor.org/rfc/rfc9562#name-version-field
645 : */
646 53598 : uuid_set_version(uuid, 7);
647 :
648 53598 : return uuid;
649 : }
650 :
651 : /*
652 : * Generate UUID version 7 with the current timestamp.
653 : */
654 : Datum
655 78 : uuidv7(PG_FUNCTION_ARGS)
656 : {
657 78 : int64 ns = get_real_time_ns_ascending();
658 78 : pg_uuid_t *uuid = generate_uuidv7(ns / NS_PER_MS, ns % NS_PER_MS);
659 :
660 78 : PG_RETURN_UUID_P(uuid);
661 : }
662 :
663 : /*
664 : * Similar to uuidv7() but with the timestamp adjusted by the given interval.
665 : */
666 : Datum
667 53520 : uuidv7_interval(PG_FUNCTION_ARGS)
668 : {
669 53520 : Interval *shift = PG_GETARG_INTERVAL_P(0);
670 : TimestampTz ts;
671 : pg_uuid_t *uuid;
672 53520 : int64 ns = get_real_time_ns_ascending();
673 : int64 us;
674 :
675 : /*
676 : * Shift the current timestamp by the given interval. To calculate time
677 : * shift correctly, we convert the UNIX epoch to TimestampTz and use
678 : * timestamptz_pl_interval(). This calculation is done with microsecond
679 : * precision.
680 : */
681 :
682 53520 : ts = (TimestampTz) (ns / NS_PER_US) -
683 : (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC;
684 :
685 : /* Compute time shift */
686 53520 : ts = DatumGetTimestampTz(DirectFunctionCall2(timestamptz_pl_interval,
687 : TimestampTzGetDatum(ts),
688 : IntervalPGetDatum(shift)));
689 :
690 : /* Convert a TimestampTz value back to an UNIX epoch timestamp */
691 53520 : us = ts + (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC;
692 :
693 : /* Generate an UUIDv7 */
694 53520 : uuid = generate_uuidv7(us / US_PER_MS, (us % US_PER_MS) * NS_PER_US + ns % NS_PER_US);
695 :
696 53520 : PG_RETURN_UUID_P(uuid);
697 : }
698 :
699 : /*
700 : * Start of a Gregorian epoch == date2j(1582,10,15)
701 : * We cast it to 64-bit because it's used in overflow-prone computations
702 : */
703 : #define GREGORIAN_EPOCH_JDATE INT64CONST(2299161)
704 :
705 : /*
706 : * Extract timestamp from UUID.
707 : *
708 : * Returns null if not RFC 9562 variant or not a version that has a timestamp.
709 : */
710 : Datum
711 53538 : uuid_extract_timestamp(PG_FUNCTION_ARGS)
712 : {
713 53538 : pg_uuid_t *uuid = PG_GETARG_UUID_P(0);
714 : int version;
715 : uint64 tms;
716 : TimestampTz ts;
717 :
718 : /* check if RFC 9562 variant */
719 53538 : if ((uuid->data[8] & 0xc0) != 0x80)
720 6 : PG_RETURN_NULL();
721 :
722 53532 : version = uuid->data[6] >> 4;
723 :
724 53532 : if (version == 1)
725 : {
726 6 : tms = ((uint64) uuid->data[0] << 24)
727 6 : + ((uint64) uuid->data[1] << 16)
728 6 : + ((uint64) uuid->data[2] << 8)
729 6 : + ((uint64) uuid->data[3])
730 6 : + ((uint64) uuid->data[4] << 40)
731 6 : + ((uint64) uuid->data[5] << 32)
732 6 : + (((uint64) uuid->data[6] & 0xf) << 56)
733 6 : + ((uint64) uuid->data[7] << 48);
734 :
735 : /* convert 100-ns intervals to us, then adjust */
736 6 : ts = (TimestampTz) (tms / 10) -
737 : ((uint64) POSTGRES_EPOCH_JDATE - GREGORIAN_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC;
738 6 : PG_RETURN_TIMESTAMPTZ(ts);
739 : }
740 :
741 53526 : if (version == 7)
742 : {
743 53520 : tms = (uuid->data[5])
744 53520 : + (((uint64) uuid->data[4]) << 8)
745 53520 : + (((uint64) uuid->data[3]) << 16)
746 53520 : + (((uint64) uuid->data[2]) << 24)
747 53520 : + (((uint64) uuid->data[1]) << 32)
748 53520 : + (((uint64) uuid->data[0]) << 40);
749 :
750 : /* convert ms to us, then adjust */
751 53520 : ts = (TimestampTz) (tms * US_PER_MS) -
752 : (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC;
753 :
754 53520 : PG_RETURN_TIMESTAMPTZ(ts);
755 : }
756 :
757 : /* not a timestamp-containing UUID version */
758 6 : PG_RETURN_NULL();
759 : }
760 :
761 : /*
762 : * Extract UUID version.
763 : *
764 : * Returns null if not RFC 9562 variant.
765 : */
766 : Datum
767 30 : uuid_extract_version(PG_FUNCTION_ARGS)
768 : {
769 30 : pg_uuid_t *uuid = PG_GETARG_UUID_P(0);
770 : uint16 version;
771 :
772 : /* check if RFC 9562 variant */
773 30 : if ((uuid->data[8] & 0xc0) != 0x80)
774 6 : PG_RETURN_NULL();
775 :
776 24 : version = uuid->data[6] >> 4;
777 :
778 24 : PG_RETURN_UINT16(version);
779 : }
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