1 /*-------------------------------------------------------------------------
2 *
3 * sequence.c
4 * PostgreSQL sequences support code.
5 *
6 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/commands/sequence.c
12 *
13 *-------------------------------------------------------------------------
14 */
15 #include "postgres.h"
16
17 #include "access/bufmask.h"
18 #include "access/htup_details.h"
19 #include "access/multixact.h"
20 #include "access/relation.h"
NUMrotationsPointInPolygon(double x0,double y0,integer n,double x[],double y[])21 #include "access/table.h"
22 #include "access/transam.h"
23 #include "access/xact.h"
24 #include "access/xlog.h"
25 #include "access/xloginsert.h"
26 #include "access/xlogutils.h"
27 #include "catalog/dependency.h"
28 #include "catalog/indexing.h"
29 #include "catalog/namespace.h"
30 #include "catalog/objectaccess.h"
31 #include "catalog/pg_sequence.h"
32 #include "catalog/pg_type.h"
33 #include "commands/defrem.h"
34 #include "commands/sequence.h"
35 #include "commands/tablecmds.h"
36 #include "funcapi.h"
37 #include "miscadmin.h"
38 #include "nodes/makefuncs.h"
39 #include "parser/parse_type.h"
40 #include "storage/lmgr.h"
41 #include "storage/proc.h"
42 #include "storage/smgr.h"
43 #include "utils/acl.h"
44 #include "utils/builtins.h"
45 #include "utils/lsyscache.h"
46 #include "utils/resowner.h"
47 #include "utils/syscache.h"
48 #include "utils/varlena.h"
49
50
51 /*
52 * We don't want to log each fetching of a value from a sequence,
53 * so we pre-log a few fetches in advance. In the event of
54 * crash we can lose (skip over) as many values as we pre-logged.
55 */
56 #define SEQ_LOG_VALS 32
57
58 /*
59 * The "special area" of a sequence's buffer page looks like this.
60 */
61 #define SEQ_MAGIC 0x1717
62
63 typedef struct sequence_magic
64 {
65 uint32 magic;
66 } sequence_magic;
67
68 /*
69 * We store a SeqTable item for every sequence we have touched in the current
70 * session. This is needed to hold onto nextval/currval state. (We can't
71 * rely on the relcache, since it's only, well, a cache, and may decide to
72 * discard entries.)
73 */
74 typedef struct SeqTableData
75 {
76 Oid relid; /* pg_class OID of this sequence (hash key) */
77 Oid filenode; /* last seen relfilenode of this sequence */
78 LocalTransactionId lxid; /* xact in which we last did a seq op */
79 bool last_valid; /* do we have a valid "last" value? */
80 int64 last; /* value last returned by nextval */
81 int64 cached; /* last value already cached for nextval */
82 /* if last != cached, we have not used up all the cached values */
83 int64 increment; /* copy of sequence's increment field */
84 /* note that increment is zero until we first do nextval_internal() */
85 } SeqTableData;
86
87 typedef SeqTableData *SeqTable;
88
89 static HTAB *seqhashtab = NULL; /* hash table for SeqTable items */
90
91 /*
92 * last_used_seq is updated by nextval() to point to the last used
93 * sequence.
94 */
95 static SeqTableData *last_used_seq = NULL;
96
97 static void fill_seq_with_data(Relation rel, HeapTuple tuple);
98 static Relation lock_and_open_sequence(SeqTable seq);
99 static void create_seq_hashtable(void);
100 static void init_sequence(Oid relid, SeqTable *p_elm, Relation *p_rel);
101 static Form_pg_sequence_data read_seq_tuple(Relation rel,
102 Buffer *buf, HeapTuple seqdatatuple);
103 static void init_params(ParseState *pstate, List *options, bool for_identity,
104 bool isInit,
105 Form_pg_sequence seqform,
106 Form_pg_sequence_data seqdataform,
107 bool *need_seq_rewrite,
108 List **owned_by);
109 static void do_setval(Oid relid, int64 next, bool iscalled);
110 static void process_owned_by(Relation seqrel, List *owned_by, bool for_identity);
111
112
113 /*
114 * DefineSequence
115 * Creates a new sequence relation
116 */
117 ObjectAddress
118 DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
119 {
120 FormData_pg_sequence seqform;
121 FormData_pg_sequence_data seqdataform;
122 bool need_seq_rewrite;
123 List *owned_by;
124 CreateStmt *stmt = makeNode(CreateStmt);
125 Oid seqoid;
126 ObjectAddress address;
127 Relation rel;
128 HeapTuple tuple;
129 TupleDesc tupDesc;
130 Datum value[SEQ_COL_LASTCOL];
131 bool null[SEQ_COL_LASTCOL];
132 Datum pgs_values[Natts_pg_sequence];
133 bool pgs_nulls[Natts_pg_sequence];
134 int i;
135
136 /* Unlogged sequences are not implemented -- not clear if useful. */
137 if (seq->sequence->relpersistence == RELPERSISTENCE_UNLOGGED)
138 ereport(ERROR,
139 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
140 errmsg("unlogged sequences are not supported")));
141
142 /*
143 * If if_not_exists was given and a relation with the same name already
144 * exists, bail out. (Note: we needn't check this when not if_not_exists,
145 * because DefineRelation will complain anyway.)
146 */
147 if (seq->if_not_exists)
148 {
149 RangeVarGetAndCheckCreationNamespace(seq->sequence, NoLock, &seqoid);
150 if (OidIsValid(seqoid))
151 {
152 ereport(NOTICE,
153 (errcode(ERRCODE_DUPLICATE_TABLE),
154 errmsg("relation \"%s\" already exists, skipping",
155 seq->sequence->relname)));
156 return InvalidObjectAddress;
157 }
158 }
159
160 /* Check and set all option values */
161 init_params(pstate, seq->options, seq->for_identity, true,
162 &seqform, &seqdataform,
163 &need_seq_rewrite, &owned_by);
164
165 /*
166 * Create relation (and fill value[] and null[] for the tuple)
167 */
168 stmt->tableElts = NIL;
169 for (i = SEQ_COL_FIRSTCOL; i <= SEQ_COL_LASTCOL; i++)
170 {
171 ColumnDef *coldef = makeNode(ColumnDef);
172
173 coldef->inhcount = 0;
174 coldef->is_local = true;
175 coldef->is_not_null = true;
176 coldef->is_from_type = false;
177 coldef->storage = 0;
178 coldef->raw_default = NULL;
179 coldef->cooked_default = NULL;
180 coldef->collClause = NULL;
181 coldef->collOid = InvalidOid;
182 coldef->constraints = NIL;
183 coldef->location = -1;
184
185 null[i - 1] = false;
186
187 switch (i)
188 {
189 case SEQ_COL_LASTVAL:
190 coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
191 coldef->colname = "last_value";
192 value[i - 1] = Int64GetDatumFast(seqdataform.last_value);
193 break;
194 case SEQ_COL_LOG:
195 coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
196 coldef->colname = "log_cnt";
197 value[i - 1] = Int64GetDatum((int64) 0);
198 break;
199 case SEQ_COL_CALLED:
200 coldef->typeName = makeTypeNameFromOid(BOOLOID, -1);
201 coldef->colname = "is_called";
202 value[i - 1] = BoolGetDatum(false);
203 break;
204 }
205 stmt->tableElts = lappend(stmt->tableElts, coldef);
206 }
207
208 stmt->relation = seq->sequence;
209 stmt->inhRelations = NIL;
210 stmt->constraints = NIL;
211 stmt->options = NIL;
212 stmt->oncommit = ONCOMMIT_NOOP;
213 stmt->tablespacename = NULL;
214 stmt->if_not_exists = seq->if_not_exists;
215
216 address = DefineRelation(stmt, RELKIND_SEQUENCE, seq->ownerId, NULL, NULL);
217 seqoid = address.objectId;
218 Assert(seqoid != InvalidOid);
219
220 rel = table_open(seqoid, AccessExclusiveLock);
221 tupDesc = RelationGetDescr(rel);
222
223 /* now initialize the sequence's data */
224 tuple = heap_form_tuple(tupDesc, value, null);
225 fill_seq_with_data(rel, tuple);
226
227 /* process OWNED BY if given */
228 if (owned_by)
229 process_owned_by(rel, owned_by, seq->for_identity);
230
231 table_close(rel, NoLock);
232
233 /* fill in pg_sequence */
234 rel = table_open(SequenceRelationId, RowExclusiveLock);
235 tupDesc = RelationGetDescr(rel);
236
237 memset(pgs_nulls, 0, sizeof(pgs_nulls));
238
239 pgs_values[Anum_pg_sequence_seqrelid - 1] = ObjectIdGetDatum(seqoid);
240 pgs_values[Anum_pg_sequence_seqtypid - 1] = ObjectIdGetDatum(seqform.seqtypid);
241 pgs_values[Anum_pg_sequence_seqstart - 1] = Int64GetDatumFast(seqform.seqstart);
242 pgs_values[Anum_pg_sequence_seqincrement - 1] = Int64GetDatumFast(seqform.seqincrement);
243 pgs_values[Anum_pg_sequence_seqmax - 1] = Int64GetDatumFast(seqform.seqmax);
244 pgs_values[Anum_pg_sequence_seqmin - 1] = Int64GetDatumFast(seqform.seqmin);
245 pgs_values[Anum_pg_sequence_seqcache - 1] = Int64GetDatumFast(seqform.seqcache);
246 pgs_values[Anum_pg_sequence_seqcycle - 1] = BoolGetDatum(seqform.seqcycle);
247
248 tuple = heap_form_tuple(tupDesc, pgs_values, pgs_nulls);
249 CatalogTupleInsert(rel, tuple);
250
251 heap_freetuple(tuple);
252 table_close(rel, RowExclusiveLock);
253
254 return address;
255 }
256
257 /*
258 * Reset a sequence to its initial value.
259 *
260 * The change is made transactionally, so that on failure of the current
261 * transaction, the sequence will be restored to its previous state.
262 * We do that by creating a whole new relfilenode for the sequence; so this
263 * works much like the rewriting forms of ALTER TABLE.
264 *
265 * Caller is assumed to have acquired AccessExclusiveLock on the sequence,
266 * which must not be released until end of transaction. Caller is also
267 * responsible for permissions checking.
268 */
269 void
270 ResetSequence(Oid seq_relid)
271 {
272 Relation seq_rel;
273 SeqTable elm;
274 Form_pg_sequence_data seq;
275 Buffer buf;
276 HeapTupleData seqdatatuple;
277 HeapTuple tuple;
278 HeapTuple pgstuple;
279 Form_pg_sequence pgsform;
280 int64 startv;
281
282 /*
283 * Read the old sequence. This does a bit more work than really
284 * necessary, but it's simple, and we do want to double-check that it's
285 * indeed a sequence.
286 */
287 init_sequence(seq_relid, &elm, &seq_rel);
288 (void) read_seq_tuple(seq_rel, &buf, &seqdatatuple);
289
290 pgstuple = SearchSysCache1(SEQRELID, ObjectIdGetDatum(seq_relid));
291 if (!HeapTupleIsValid(pgstuple))
292 elog(ERROR, "cache lookup failed for sequence %u", seq_relid);
293 pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
294 startv = pgsform->seqstart;
295 ReleaseSysCache(pgstuple);
296
297 /*
298 * Copy the existing sequence tuple.
299 */
300 tuple = heap_copytuple(&seqdatatuple);
301
302 /* Now we're done with the old page */
303 UnlockReleaseBuffer(buf);
304
305 /*
306 * Modify the copied tuple to execute the restart (compare the RESTART
307 * action in AlterSequence)
308 */
309 seq = (Form_pg_sequence_data) GETSTRUCT(tuple);
310 seq->last_value = startv;
311 seq->is_called = false;
312 seq->log_cnt = 0;
313
314 /*
315 * Create a new storage file for the sequence.
316 */
317 RelationSetNewRelfilenode(seq_rel, seq_rel->rd_rel->relpersistence);
318
319 /*
320 * Ensure sequence's relfrozenxid is at 0, since it won't contain any
321 * unfrozen XIDs. Same with relminmxid, since a sequence will never
322 * contain multixacts.
323 */
324 Assert(seq_rel->rd_rel->relfrozenxid == InvalidTransactionId);
325 Assert(seq_rel->rd_rel->relminmxid == InvalidMultiXactId);
326
327 /*
328 * Insert the modified tuple into the new storage file.
329 */
330 fill_seq_with_data(seq_rel, tuple);
331
332 /* Clear local cache so that we don't think we have cached numbers */
333 /* Note that we do not change the currval() state */
334 elm->cached = elm->last;
335
336 relation_close(seq_rel, NoLock);
337 }
338
339 /*
340 * Initialize a sequence's relation with the specified tuple as content
341 */
342 static void
343 fill_seq_with_data(Relation rel, HeapTuple tuple)
344 {
345 Buffer buf;
346 Page page;
347 sequence_magic *sm;
348 OffsetNumber offnum;
349
350 /* Initialize first page of relation with special magic number */
351
352 buf = ReadBuffer(rel, P_NEW);
353 Assert(BufferGetBlockNumber(buf) == 0);
354
355 page = BufferGetPage(buf);
356
357 PageInit(page, BufferGetPageSize(buf), sizeof(sequence_magic));
358 sm = (sequence_magic *) PageGetSpecialPointer(page);
359 sm->magic = SEQ_MAGIC;
360
361 /* Now insert sequence tuple */
362
363 LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
364
365 /*
366 * Since VACUUM does not process sequences, we have to force the tuple to
367 * have xmin = FrozenTransactionId now. Otherwise it would become
368 * invisible to SELECTs after 2G transactions. It is okay to do this
369 * because if the current transaction aborts, no other xact will ever
370 * examine the sequence tuple anyway.
371 */
372 HeapTupleHeaderSetXmin(tuple->t_data, FrozenTransactionId);
373 HeapTupleHeaderSetXminFrozen(tuple->t_data);
374 HeapTupleHeaderSetCmin(tuple->t_data, FirstCommandId);
375 HeapTupleHeaderSetXmax(tuple->t_data, InvalidTransactionId);
376 tuple->t_data->t_infomask |= HEAP_XMAX_INVALID;
377 ItemPointerSet(&tuple->t_data->t_ctid, 0, FirstOffsetNumber);
378
379 /* check the comment above nextval_internal()'s equivalent call. */
380 if (RelationNeedsWAL(rel))
381 GetTopTransactionId();
382
383 START_CRIT_SECTION();
384
385 MarkBufferDirty(buf);
386
387 offnum = PageAddItem(page, (Item) tuple->t_data, tuple->t_len,
388 InvalidOffsetNumber, false, false);
389 if (offnum != FirstOffsetNumber)
390 elog(ERROR, "failed to add sequence tuple to page");
391
392 /* XLOG stuff */
393 if (RelationNeedsWAL(rel))
394 {
395 xl_seq_rec xlrec;
396 XLogRecPtr recptr;
397
398 XLogBeginInsert();
399 XLogRegisterBuffer(0, buf, REGBUF_WILL_INIT);
400
401 xlrec.node = rel->rd_node;
402
403 XLogRegisterData((char *) &xlrec, sizeof(xl_seq_rec));
404 XLogRegisterData((char *) tuple->t_data, tuple->t_len);
405
406 recptr = XLogInsert(RM_SEQ_ID, XLOG_SEQ_LOG);
407
408 PageSetLSN(page, recptr);
409 }
410
411 END_CRIT_SECTION();
412
413 UnlockReleaseBuffer(buf);
414 }
415
416 /*
417 * AlterSequence
418 *
419 * Modify the definition of a sequence relation
420 */
421 ObjectAddress
422 AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
423 {
424 Oid relid;
425 SeqTable elm;
426 Relation seqrel;
427 Buffer buf;
428 HeapTupleData datatuple;
429 Form_pg_sequence seqform;
430 Form_pg_sequence_data newdataform;
431 bool need_seq_rewrite;
432 List *owned_by;
433 ObjectAddress address;
434 Relation rel;
435 HeapTuple seqtuple;
436 HeapTuple newdatatuple;
437
438 /* Open and lock sequence, and check for ownership along the way. */
439 relid = RangeVarGetRelidExtended(stmt->sequence,
440 ShareRowExclusiveLock,
441 stmt->missing_ok ? RVR_MISSING_OK : 0,
442 RangeVarCallbackOwnsRelation,
443 NULL);
444 if (relid == InvalidOid)
445 {
446 ereport(NOTICE,
447 (errmsg("relation \"%s\" does not exist, skipping",
448 stmt->sequence->relname)));
449 return InvalidObjectAddress;
450 }
451
452 init_sequence(relid, &elm, &seqrel);
453
454 rel = table_open(SequenceRelationId, RowExclusiveLock);
455 seqtuple = SearchSysCacheCopy1(SEQRELID,
456 ObjectIdGetDatum(relid));
457 if (!HeapTupleIsValid(seqtuple))
458 elog(ERROR, "cache lookup failed for sequence %u",
459 relid);
460
461 seqform = (Form_pg_sequence) GETSTRUCT(seqtuple);
462
463 /* lock page's buffer and read tuple into new sequence structure */
464 (void) read_seq_tuple(seqrel, &buf, &datatuple);
465
466 /* copy the existing sequence data tuple, so it can be modified locally */
467 newdatatuple = heap_copytuple(&datatuple);
468 newdataform = (Form_pg_sequence_data) GETSTRUCT(newdatatuple);
469
470 UnlockReleaseBuffer(buf);
471
472 /* Check and set new values */
473 init_params(pstate, stmt->options, stmt->for_identity, false,
474 seqform, newdataform,
475 &need_seq_rewrite, &owned_by);
476
477 /* Clear local cache so that we don't think we have cached numbers */
478 /* Note that we do not change the currval() state */
479 elm->cached = elm->last;
480
481 /* If needed, rewrite the sequence relation itself */
482 if (need_seq_rewrite)
483 {
484 /* check the comment above nextval_internal()'s equivalent call. */
485 if (RelationNeedsWAL(seqrel))
486 GetTopTransactionId();
487
488 /*
489 * Create a new storage file for the sequence, making the state
490 * changes transactional.
491 */
492 RelationSetNewRelfilenode(seqrel, seqrel->rd_rel->relpersistence);
493
494 /*
495 * Ensure sequence's relfrozenxid is at 0, since it won't contain any
496 * unfrozen XIDs. Same with relminmxid, since a sequence will never
497 * contain multixacts.
498 */
499 Assert(seqrel->rd_rel->relfrozenxid == InvalidTransactionId);
500 Assert(seqrel->rd_rel->relminmxid == InvalidMultiXactId);
501
502 /*
503 * Insert the modified tuple into the new storage file.
504 */
505 fill_seq_with_data(seqrel, newdatatuple);
506 }
507
508 /* process OWNED BY if given */
509 if (owned_by)
510 process_owned_by(seqrel, owned_by, stmt->for_identity);
511
512 /* update the pg_sequence tuple (we could skip this in some cases...) */
513 CatalogTupleUpdate(rel, &seqtuple->t_self, seqtuple);
514
515 InvokeObjectPostAlterHook(RelationRelationId, relid, 0);
516
517 ObjectAddressSet(address, RelationRelationId, relid);
518
519 table_close(rel, RowExclusiveLock);
520 relation_close(seqrel, NoLock);
521
522 return address;
523 }
524
525 void
526 DeleteSequenceTuple(Oid relid)
527 {
528 Relation rel;
529 HeapTuple tuple;
530
531 rel = table_open(SequenceRelationId, RowExclusiveLock);
532
533 tuple = SearchSysCache1(SEQRELID, ObjectIdGetDatum(relid));
534 if (!HeapTupleIsValid(tuple))
535 elog(ERROR, "cache lookup failed for sequence %u", relid);
536
537 CatalogTupleDelete(rel, &tuple->t_self);
538
539 ReleaseSysCache(tuple);
540 table_close(rel, RowExclusiveLock);
541 }
542
543 /*
544 * Note: nextval with a text argument is no longer exported as a pg_proc
545 * entry, but we keep it around to ease porting of C code that may have
546 * called the function directly.
547 */
548 Datum
549 nextval(PG_FUNCTION_ARGS)
550 {
551 text *seqin = PG_GETARG_TEXT_PP(0);
552 RangeVar *sequence;
553 Oid relid;
554
555 sequence = makeRangeVarFromNameList(textToQualifiedNameList(seqin));
556
557 /*
558 * XXX: This is not safe in the presence of concurrent DDL, but acquiring
559 * a lock here is more expensive than letting nextval_internal do it,
560 * since the latter maintains a cache that keeps us from hitting the lock
561 * manager more than once per transaction. It's not clear whether the
562 * performance penalty is material in practice, but for now, we do it this
563 * way.
564 */
565 relid = RangeVarGetRelid(sequence, NoLock, false);
566
567 PG_RETURN_INT64(nextval_internal(relid, true));
568 }
569
570 Datum
571 nextval_oid(PG_FUNCTION_ARGS)
572 {
573 Oid relid = PG_GETARG_OID(0);
574
575 PG_RETURN_INT64(nextval_internal(relid, true));
576 }
577
578 int64
579 nextval_internal(Oid relid, bool check_permissions)
580 {
581 SeqTable elm;
582 Relation seqrel;
583 Buffer buf;
584 Page page;
585 HeapTuple pgstuple;
586 Form_pg_sequence pgsform;
587 HeapTupleData seqdatatuple;
588 Form_pg_sequence_data seq;
589 int64 incby,
590 maxv,
591 minv,
592 cache,
593 log,
594 fetch,
595 last;
596 int64 result,
597 next,
598 rescnt = 0;
599 bool cycle;
600 bool logit = false;
601
602 /* open and lock sequence */
603 init_sequence(relid, &elm, &seqrel);
604
605 if (check_permissions &&
606 pg_class_aclcheck(elm->relid, GetUserId(),
607 ACL_USAGE | ACL_UPDATE) != ACLCHECK_OK)
608 ereport(ERROR,
609 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
610 errmsg("permission denied for sequence %s",
611 RelationGetRelationName(seqrel))));
612
613 /* read-only transactions may only modify temp sequences */
614 if (!seqrel->rd_islocaltemp)
615 PreventCommandIfReadOnly("nextval()");
616
617 /*
618 * Forbid this during parallel operation because, to make it work, the
619 * cooperating backends would need to share the backend-local cached
620 * sequence information. Currently, we don't support that.
621 */
622 PreventCommandIfParallelMode("nextval()");
623
624 if (elm->last != elm->cached) /* some numbers were cached */
625 {
626 Assert(elm->last_valid);
627 Assert(elm->increment != 0);
628 elm->last += elm->increment;
629 relation_close(seqrel, NoLock);
630 last_used_seq = elm;
631 return elm->last;
632 }
633
634 pgstuple = SearchSysCache1(SEQRELID, ObjectIdGetDatum(relid));
635 if (!HeapTupleIsValid(pgstuple))
636 elog(ERROR, "cache lookup failed for sequence %u", relid);
637 pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
638 incby = pgsform->seqincrement;
639 maxv = pgsform->seqmax;
640 minv = pgsform->seqmin;
641 cache = pgsform->seqcache;
642 cycle = pgsform->seqcycle;
643 ReleaseSysCache(pgstuple);
644
645 /* lock page' buffer and read tuple */
646 seq = read_seq_tuple(seqrel, &buf, &seqdatatuple);
647 page = BufferGetPage(buf);
648
649 elm->increment = incby;
650 last = next = result = seq->last_value;
651 fetch = cache;
652 log = seq->log_cnt;
653
654 if (!seq->is_called)
655 {
656 rescnt++; /* return last_value if not is_called */
657 fetch--;
658 }
659
660 /*
661 * Decide whether we should emit a WAL log record. If so, force up the
662 * fetch count to grab SEQ_LOG_VALS more values than we actually need to
663 * cache. (These will then be usable without logging.)
664 *
665 * If this is the first nextval after a checkpoint, we must force a new
666 * WAL record to be written anyway, else replay starting from the
667 * checkpoint would fail to advance the sequence past the logged values.
668 * In this case we may as well fetch extra values.
669 */
670 if (log < fetch || !seq->is_called)
671 {
672 /* forced log to satisfy local demand for values */
673 fetch = log = fetch + SEQ_LOG_VALS;
674 logit = true;
675 }
676 else
677 {
678 XLogRecPtr redoptr = GetRedoRecPtr();
679
680 if (PageGetLSN(page) <= redoptr)
681 {
682 /* last update of seq was before checkpoint */
683 fetch = log = fetch + SEQ_LOG_VALS;
684 logit = true;
685 }
686 }
687
688 while (fetch) /* try to fetch cache [+ log ] numbers */
689 {
690 /*
691 * Check MAXVALUE for ascending sequences and MINVALUE for descending
692 * sequences
693 */
694 if (incby > 0)
695 {
696 /* ascending sequence */
697 if ((maxv >= 0 && next > maxv - incby) ||
698 (maxv < 0 && next + incby > maxv))
699 {
700 if (rescnt > 0)
701 break; /* stop fetching */
702 if (!cycle)
703 {
704 char buf[100];
705
706 snprintf(buf, sizeof(buf), INT64_FORMAT, maxv);
707 ereport(ERROR,
708 (errcode(ERRCODE_SEQUENCE_GENERATOR_LIMIT_EXCEEDED),
709 errmsg("nextval: reached maximum value of sequence \"%s\" (%s)",
710 RelationGetRelationName(seqrel), buf)));
711 }
712 next = minv;
713 }
714 else
715 next += incby;
716 }
717 else
718 {
719 /* descending sequence */
720 if ((minv < 0 && next < minv - incby) ||
721 (minv >= 0 && next + incby < minv))
722 {
723 if (rescnt > 0)
724 break; /* stop fetching */
725 if (!cycle)
726 {
727 char buf[100];
728
729 snprintf(buf, sizeof(buf), INT64_FORMAT, minv);
730 ereport(ERROR,
731 (errcode(ERRCODE_SEQUENCE_GENERATOR_LIMIT_EXCEEDED),
732 errmsg("nextval: reached minimum value of sequence \"%s\" (%s)",
733 RelationGetRelationName(seqrel), buf)));
734 }
735 next = maxv;
736 }
737 else
738 next += incby;
739 }
740 fetch--;
741 if (rescnt < cache)
742 {
743 log--;
744 rescnt++;
745 last = next;
746 if (rescnt == 1) /* if it's first result - */
747 result = next; /* it's what to return */
748 }
749 }
750
751 log -= fetch; /* adjust for any unfetched numbers */
752 Assert(log >= 0);
753
754 /* save info in local cache */
755 elm->last = result; /* last returned number */
756 elm->cached = last; /* last fetched number */
757 elm->last_valid = true;
758
759 last_used_seq = elm;
760
761 /*
762 * If something needs to be WAL logged, acquire an xid, so this
763 * transaction's commit will trigger a WAL flush and wait for syncrep.
764 * It's sufficient to ensure the toplevel transaction has an xid, no need
765 * to assign xids subxacts, that'll already trigger an appropriate wait.
766 * (Have to do that here, so we're outside the critical section)
767 */
768 if (logit && RelationNeedsWAL(seqrel))
769 GetTopTransactionId();
770
771 /* ready to change the on-disk (or really, in-buffer) tuple */
772 START_CRIT_SECTION();
773
774 /*
775 * We must mark the buffer dirty before doing XLogInsert(); see notes in
776 * SyncOneBuffer(). However, we don't apply the desired changes just yet.
777 * This looks like a violation of the buffer update protocol, but it is in
778 * fact safe because we hold exclusive lock on the buffer. Any other
779 * process, including a checkpoint, that tries to examine the buffer
780 * contents will block until we release the lock, and then will see the
781 * final state that we install below.
782 */
783 MarkBufferDirty(buf);
784
785 /* XLOG stuff */
786 if (logit && RelationNeedsWAL(seqrel))
787 {
788 xl_seq_rec xlrec;
789 XLogRecPtr recptr;
790
791 /*
792 * We don't log the current state of the tuple, but rather the state
793 * as it would appear after "log" more fetches. This lets us skip
794 * that many future WAL records, at the cost that we lose those
795 * sequence values if we crash.
796 */
797 XLogBeginInsert();
798 XLogRegisterBuffer(0, buf, REGBUF_WILL_INIT);
799
800 /* set values that will be saved in xlog */
801 seq->last_value = next;
802 seq->is_called = true;
803 seq->log_cnt = 0;
804
805 xlrec.node = seqrel->rd_node;
806
807 XLogRegisterData((char *) &xlrec, sizeof(xl_seq_rec));
808 XLogRegisterData((char *) seqdatatuple.t_data, seqdatatuple.t_len);
809
810 recptr = XLogInsert(RM_SEQ_ID, XLOG_SEQ_LOG);
811
812 PageSetLSN(page, recptr);
813 }
814
815 /* Now update sequence tuple to the intended final state */
816 seq->last_value = last; /* last fetched number */
817 seq->is_called = true;
818 seq->log_cnt = log; /* how much is logged */
819
820 END_CRIT_SECTION();
821
822 UnlockReleaseBuffer(buf);
823
824 relation_close(seqrel, NoLock);
825
826 return result;
827 }
828
829 Datum
830 currval_oid(PG_FUNCTION_ARGS)
831 {
832 Oid relid = PG_GETARG_OID(0);
833 int64 result;
834 SeqTable elm;
835 Relation seqrel;
836
837 /* open and lock sequence */
838 init_sequence(relid, &elm, &seqrel);
839
840 if (pg_class_aclcheck(elm->relid, GetUserId(),
841 ACL_SELECT | ACL_USAGE) != ACLCHECK_OK)
842 ereport(ERROR,
843 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
844 errmsg("permission denied for sequence %s",
845 RelationGetRelationName(seqrel))));
846
847 if (!elm->last_valid)
848 ereport(ERROR,
849 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
850 errmsg("currval of sequence \"%s\" is not yet defined in this session",
851 RelationGetRelationName(seqrel))));
852
853 result = elm->last;
854
855 relation_close(seqrel, NoLock);
856
857 PG_RETURN_INT64(result);
858 }
859
860 Datum
861 lastval(PG_FUNCTION_ARGS)
862 {
863 Relation seqrel;
864 int64 result;
865
866 if (last_used_seq == NULL)
867 ereport(ERROR,
868 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
869 errmsg("lastval is not yet defined in this session")));
870
871 /* Someone may have dropped the sequence since the last nextval() */
872 if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(last_used_seq->relid)))
873 ereport(ERROR,
874 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
875 errmsg("lastval is not yet defined in this session")));
876
877 seqrel = lock_and_open_sequence(last_used_seq);
878
879 /* nextval() must have already been called for this sequence */
880 Assert(last_used_seq->last_valid);
881
882 if (pg_class_aclcheck(last_used_seq->relid, GetUserId(),
883 ACL_SELECT | ACL_USAGE) != ACLCHECK_OK)
884 ereport(ERROR,
885 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
886 errmsg("permission denied for sequence %s",
887 RelationGetRelationName(seqrel))));
888
889 result = last_used_seq->last;
890 relation_close(seqrel, NoLock);
891
892 PG_RETURN_INT64(result);
893 }
894
895 /*
896 * Main internal procedure that handles 2 & 3 arg forms of SETVAL.
897 *
898 * Note that the 3 arg version (which sets the is_called flag) is
899 * only for use in pg_dump, and setting the is_called flag may not
900 * work if multiple users are attached to the database and referencing
901 * the sequence (unlikely if pg_dump is restoring it).
902 *
903 * It is necessary to have the 3 arg version so that pg_dump can
904 * restore the state of a sequence exactly during data-only restores -
905 * it is the only way to clear the is_called flag in an existing
906 * sequence.
907 */
908 static void
909 do_setval(Oid relid, int64 next, bool iscalled)
910 {
911 SeqTable elm;
912 Relation seqrel;
913 Buffer buf;
914 HeapTupleData seqdatatuple;
915 Form_pg_sequence_data seq;
916 HeapTuple pgstuple;
917 Form_pg_sequence pgsform;
918 int64 maxv,
919 minv;
920
921 /* open and lock sequence */
922 init_sequence(relid, &elm, &seqrel);
923
924 if (pg_class_aclcheck(elm->relid, GetUserId(), ACL_UPDATE) != ACLCHECK_OK)
925 ereport(ERROR,
926 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
927 errmsg("permission denied for sequence %s",
928 RelationGetRelationName(seqrel))));
929
930 pgstuple = SearchSysCache1(SEQRELID, ObjectIdGetDatum(relid));
931 if (!HeapTupleIsValid(pgstuple))
932 elog(ERROR, "cache lookup failed for sequence %u", relid);
933 pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
934 maxv = pgsform->seqmax;
935 minv = pgsform->seqmin;
936 ReleaseSysCache(pgstuple);
937
938 /* read-only transactions may only modify temp sequences */
939 if (!seqrel->rd_islocaltemp)
940 PreventCommandIfReadOnly("setval()");
941
942 /*
943 * Forbid this during parallel operation because, to make it work, the
944 * cooperating backends would need to share the backend-local cached
945 * sequence information. Currently, we don't support that.
946 */
947 PreventCommandIfParallelMode("setval()");
948
949 /* lock page' buffer and read tuple */
950 seq = read_seq_tuple(seqrel, &buf, &seqdatatuple);
951
952 if ((next < minv) || (next > maxv))
953 {
954 char bufv[100],
955 bufm[100],
956 bufx[100];
957
958 snprintf(bufv, sizeof(bufv), INT64_FORMAT, next);
959 snprintf(bufm, sizeof(bufm), INT64_FORMAT, minv);
960 snprintf(bufx, sizeof(bufx), INT64_FORMAT, maxv);
961 ereport(ERROR,
962 (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
963 errmsg("setval: value %s is out of bounds for sequence \"%s\" (%s..%s)",
964 bufv, RelationGetRelationName(seqrel),
965 bufm, bufx)));
966 }
967
968 /* Set the currval() state only if iscalled = true */
969 if (iscalled)
970 {
971 elm->last = next; /* last returned number */
972 elm->last_valid = true;
973 }
974
975 /* In any case, forget any future cached numbers */
976 elm->cached = elm->last;
977
978 /* check the comment above nextval_internal()'s equivalent call. */
979 if (RelationNeedsWAL(seqrel))
980 GetTopTransactionId();
981
982 /* ready to change the on-disk (or really, in-buffer) tuple */
983 START_CRIT_SECTION();
984
985 seq->last_value = next; /* last fetched number */
986 seq->is_called = iscalled;
987 seq->log_cnt = 0;
988
989 MarkBufferDirty(buf);
990
991 /* XLOG stuff */
992 if (RelationNeedsWAL(seqrel))
993 {
994 xl_seq_rec xlrec;
995 XLogRecPtr recptr;
996 Page page = BufferGetPage(buf);
997
998 XLogBeginInsert();
999 XLogRegisterBuffer(0, buf, REGBUF_WILL_INIT);
1000
1001 xlrec.node = seqrel->rd_node;
1002 XLogRegisterData((char *) &xlrec, sizeof(xl_seq_rec));
1003 XLogRegisterData((char *) seqdatatuple.t_data, seqdatatuple.t_len);
1004
1005 recptr = XLogInsert(RM_SEQ_ID, XLOG_SEQ_LOG);
1006
1007 PageSetLSN(page, recptr);
1008 }
1009
1010 END_CRIT_SECTION();
1011
1012 UnlockReleaseBuffer(buf);
1013
1014 relation_close(seqrel, NoLock);
1015 }
1016
1017 /*
1018 * Implement the 2 arg setval procedure.
1019 * See do_setval for discussion.
1020 */
1021 Datum
1022 setval_oid(PG_FUNCTION_ARGS)
1023 {
1024 Oid relid = PG_GETARG_OID(0);
1025 int64 next = PG_GETARG_INT64(1);
1026
1027 do_setval(relid, next, true);
1028
1029 PG_RETURN_INT64(next);
1030 }
1031
1032 /*
1033 * Implement the 3 arg setval procedure.
1034 * See do_setval for discussion.
1035 */
1036 Datum
1037 setval3_oid(PG_FUNCTION_ARGS)
1038 {
1039 Oid relid = PG_GETARG_OID(0);
1040 int64 next = PG_GETARG_INT64(1);
1041 bool iscalled = PG_GETARG_BOOL(2);
1042
1043 do_setval(relid, next, iscalled);
1044
1045 PG_RETURN_INT64(next);
1046 }
1047
1048
1049 /*
1050 * Open the sequence and acquire lock if needed
1051 *
1052 * If we haven't touched the sequence already in this transaction,
1053 * we need to acquire a lock. We arrange for the lock to
1054 * be owned by the top transaction, so that we don't need to do it
1055 * more than once per xact.
1056 */
1057 static Relation
1058 lock_and_open_sequence(SeqTable seq)
1059 {
1060 LocalTransactionId thislxid = MyProc->lxid;
1061
1062 /* Get the lock if not already held in this xact */
1063 if (seq->lxid != thislxid)
1064 {
1065 ResourceOwner currentOwner;
1066
1067 currentOwner = CurrentResourceOwner;
1068 CurrentResourceOwner = TopTransactionResourceOwner;
1069
1070 LockRelationOid(seq->relid, RowExclusiveLock);
1071
1072 CurrentResourceOwner = currentOwner;
1073
1074 /* Flag that we have a lock in the current xact */
1075 seq->lxid = thislxid;
1076 }
1077
1078 /* We now know we have the lock, and can safely open the rel */
1079 return relation_open(seq->relid, NoLock);
1080 }
1081
1082 /*
1083 * Creates the hash table for storing sequence data
1084 */
1085 static void
1086 create_seq_hashtable(void)
1087 {
1088 HASHCTL ctl;
1089
1090 memset(&ctl, 0, sizeof(ctl));
1091 ctl.keysize = sizeof(Oid);
1092 ctl.entrysize = sizeof(SeqTableData);
1093
1094 seqhashtab = hash_create("Sequence values", 16, &ctl,
1095 HASH_ELEM | HASH_BLOBS);
1096 }
1097
1098 /*
1099 * Given a relation OID, open and lock the sequence. p_elm and p_rel are
1100 * output parameters.
1101 */
1102 static void
1103 init_sequence(Oid relid, SeqTable *p_elm, Relation *p_rel)
1104 {
1105 SeqTable elm;
1106 Relation seqrel;
1107 bool found;
1108
1109 /* Find or create a hash table entry for this sequence */
1110 if (seqhashtab == NULL)
1111 create_seq_hashtable();
1112
1113 elm = (SeqTable) hash_search(seqhashtab, &relid, HASH_ENTER, &found);
1114
1115 /*
1116 * Initialize the new hash table entry if it did not exist already.
1117 *
1118 * NOTE: seqtable entries are stored for the life of a backend (unless
1119 * explicitly discarded with DISCARD). If the sequence itself is deleted
1120 * then the entry becomes wasted memory, but it's small enough that this
1121 * should not matter.
1122 */
1123 if (!found)
1124 {
1125 /* relid already filled in */
1126 elm->filenode = InvalidOid;
1127 elm->lxid = InvalidLocalTransactionId;
1128 elm->last_valid = false;
1129 elm->last = elm->cached = 0;
1130 }
1131
1132 /*
1133 * Open the sequence relation.
1134 */
1135 seqrel = lock_and_open_sequence(elm);
1136
1137 if (seqrel->rd_rel->relkind != RELKIND_SEQUENCE)
1138 ereport(ERROR,
1139 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
1140 errmsg("\"%s\" is not a sequence",
1141 RelationGetRelationName(seqrel))));
1142
1143 /*
1144 * If the sequence has been transactionally replaced since we last saw it,
1145 * discard any cached-but-unissued values. We do not touch the currval()
1146 * state, however.
1147 */
1148 if (seqrel->rd_rel->relfilenode != elm->filenode)
1149 {
1150 elm->filenode = seqrel->rd_rel->relfilenode;
1151 elm->cached = elm->last;
1152 }
1153
1154 /* Return results */
1155 *p_elm = elm;
1156 *p_rel = seqrel;
1157 }
1158
1159
1160 /*
1161 * Given an opened sequence relation, lock the page buffer and find the tuple
1162 *
1163 * *buf receives the reference to the pinned-and-ex-locked buffer
1164 * *seqdatatuple receives the reference to the sequence tuple proper
1165 * (this arg should point to a local variable of type HeapTupleData)
1166 *
1167 * Function's return value points to the data payload of the tuple
1168 */
1169 static Form_pg_sequence_data
1170 read_seq_tuple(Relation rel, Buffer *buf, HeapTuple seqdatatuple)
1171 {
1172 Page page;
1173 ItemId lp;
1174 sequence_magic *sm;
1175 Form_pg_sequence_data seq;
1176
1177 *buf = ReadBuffer(rel, 0);
1178 LockBuffer(*buf, BUFFER_LOCK_EXCLUSIVE);
1179
1180 page = BufferGetPage(*buf);
1181 sm = (sequence_magic *) PageGetSpecialPointer(page);
1182
1183 if (sm->magic != SEQ_MAGIC)
1184 elog(ERROR, "bad magic number in sequence \"%s\": %08X",
1185 RelationGetRelationName(rel), sm->magic);
1186
1187 lp = PageGetItemId(page, FirstOffsetNumber);
1188 Assert(ItemIdIsNormal(lp));
1189
1190 /* Note we currently only bother to set these two fields of *seqdatatuple */
1191 seqdatatuple->t_data = (HeapTupleHeader) PageGetItem(page, lp);
1192 seqdatatuple->t_len = ItemIdGetLength(lp);
1193
1194 /*
1195 * Previous releases of Postgres neglected to prevent SELECT FOR UPDATE on
1196 * a sequence, which would leave a non-frozen XID in the sequence tuple's
1197 * xmax, which eventually leads to clog access failures or worse. If we
1198 * see this has happened, clean up after it. We treat this like a hint
1199 * bit update, ie, don't bother to WAL-log it, since we can certainly do
1200 * this again if the update gets lost.
1201 */
1202 Assert(!(seqdatatuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI));
1203 if (HeapTupleHeaderGetRawXmax(seqdatatuple->t_data) != InvalidTransactionId)
1204 {
1205 HeapTupleHeaderSetXmax(seqdatatuple->t_data, InvalidTransactionId);
1206 seqdatatuple->t_data->t_infomask &= ~HEAP_XMAX_COMMITTED;
1207 seqdatatuple->t_data->t_infomask |= HEAP_XMAX_INVALID;
1208 MarkBufferDirtyHint(*buf, true);
1209 }
1210
1211 seq = (Form_pg_sequence_data) GETSTRUCT(seqdatatuple);
1212
1213 return seq;
1214 }
1215
1216 /*
1217 * init_params: process the options list of CREATE or ALTER SEQUENCE, and
1218 * store the values into appropriate fields of seqform, for changes that go
1219 * into the pg_sequence catalog, and fields of seqdataform for changes to the
1220 * sequence relation itself. Set *need_seq_rewrite to true if we changed any
1221 * parameters that require rewriting the sequence's relation (interesting for
1222 * ALTER SEQUENCE). Also set *owned_by to any OWNED BY option, or to NIL if
1223 * there is none.
1224 *
1225 * If isInit is true, fill any unspecified options with default values;
1226 * otherwise, do not change existing options that aren't explicitly overridden.
1227 *
1228 * Note: we force a sequence rewrite whenever we change parameters that affect
1229 * generation of future sequence values, even if the seqdataform per se is not
1230 * changed. This allows ALTER SEQUENCE to behave transactionally. Currently,
1231 * the only option that doesn't cause that is OWNED BY. It's *necessary* for
1232 * ALTER SEQUENCE OWNED BY to not rewrite the sequence, because that would
1233 * break pg_upgrade by causing unwanted changes in the sequence's relfilenode.
1234 */
1235 static void
1236 init_params(ParseState *pstate, List *options, bool for_identity,
1237 bool isInit,
1238 Form_pg_sequence seqform,
1239 Form_pg_sequence_data seqdataform,
1240 bool *need_seq_rewrite,
1241 List **owned_by)
1242 {
1243 DefElem *as_type = NULL;
1244 DefElem *start_value = NULL;
1245 DefElem *restart_value = NULL;
1246 DefElem *increment_by = NULL;
1247 DefElem *max_value = NULL;
1248 DefElem *min_value = NULL;
1249 DefElem *cache_value = NULL;
1250 DefElem *is_cycled = NULL;
1251 ListCell *option;
1252 bool reset_max_value = false;
1253 bool reset_min_value = false;
1254
1255 *need_seq_rewrite = false;
1256 *owned_by = NIL;
1257
1258 foreach(option, options)
1259 {
1260 DefElem *defel = (DefElem *) lfirst(option);
1261
1262 if (strcmp(defel->defname, "as") == 0)
1263 {
1264 if (as_type)
1265 ereport(ERROR,
1266 (errcode(ERRCODE_SYNTAX_ERROR),
1267 errmsg("conflicting or redundant options"),
1268 parser_errposition(pstate, defel->location)));
1269 as_type = defel;
1270 *need_seq_rewrite = true;
1271 }
1272 else if (strcmp(defel->defname, "increment") == 0)
1273 {
1274 if (increment_by)
1275 ereport(ERROR,
1276 (errcode(ERRCODE_SYNTAX_ERROR),
1277 errmsg("conflicting or redundant options"),
1278 parser_errposition(pstate, defel->location)));
1279 increment_by = defel;
1280 *need_seq_rewrite = true;
1281 }
1282 else if (strcmp(defel->defname, "start") == 0)
1283 {
1284 if (start_value)
1285 ereport(ERROR,
1286 (errcode(ERRCODE_SYNTAX_ERROR),
1287 errmsg("conflicting or redundant options"),
1288 parser_errposition(pstate, defel->location)));
1289 start_value = defel;
1290 *need_seq_rewrite = true;
1291 }
1292 else if (strcmp(defel->defname, "restart") == 0)
1293 {
1294 if (restart_value)
1295 ereport(ERROR,
1296 (errcode(ERRCODE_SYNTAX_ERROR),
1297 errmsg("conflicting or redundant options"),
1298 parser_errposition(pstate, defel->location)));
1299 restart_value = defel;
1300 *need_seq_rewrite = true;
1301 }
1302 else if (strcmp(defel->defname, "maxvalue") == 0)
1303 {
1304 if (max_value)
1305 ereport(ERROR,
1306 (errcode(ERRCODE_SYNTAX_ERROR),
1307 errmsg("conflicting or redundant options"),
1308 parser_errposition(pstate, defel->location)));
1309 max_value = defel;
1310 *need_seq_rewrite = true;
1311 }
1312 else if (strcmp(defel->defname, "minvalue") == 0)
1313 {
1314 if (min_value)
1315 ereport(ERROR,
1316 (errcode(ERRCODE_SYNTAX_ERROR),
1317 errmsg("conflicting or redundant options"),
1318 parser_errposition(pstate, defel->location)));
1319 min_value = defel;
1320 *need_seq_rewrite = true;
1321 }
1322 else if (strcmp(defel->defname, "cache") == 0)
1323 {
1324 if (cache_value)
1325 ereport(ERROR,
1326 (errcode(ERRCODE_SYNTAX_ERROR),
1327 errmsg("conflicting or redundant options"),
1328 parser_errposition(pstate, defel->location)));
1329 cache_value = defel;
1330 *need_seq_rewrite = true;
1331 }
1332 else if (strcmp(defel->defname, "cycle") == 0)
1333 {
1334 if (is_cycled)
1335 ereport(ERROR,
1336 (errcode(ERRCODE_SYNTAX_ERROR),
1337 errmsg("conflicting or redundant options"),
1338 parser_errposition(pstate, defel->location)));
1339 is_cycled = defel;
1340 *need_seq_rewrite = true;
1341 }
1342 else if (strcmp(defel->defname, "owned_by") == 0)
1343 {
1344 if (*owned_by)
1345 ereport(ERROR,
1346 (errcode(ERRCODE_SYNTAX_ERROR),
1347 errmsg("conflicting or redundant options"),
1348 parser_errposition(pstate, defel->location)));
1349 *owned_by = defGetQualifiedName(defel);
1350 }
1351 else if (strcmp(defel->defname, "sequence_name") == 0)
1352 {
1353 /*
1354 * The parser allows this, but it is only for identity columns, in
1355 * which case it is filtered out in parse_utilcmd.c. We only get
1356 * here if someone puts it into a CREATE SEQUENCE.
1357 */
1358 ereport(ERROR,
1359 (errcode(ERRCODE_SYNTAX_ERROR),
1360 errmsg("invalid sequence option SEQUENCE NAME"),
1361 parser_errposition(pstate, defel->location)));
1362 }
1363 else
1364 elog(ERROR, "option \"%s\" not recognized",
1365 defel->defname);
1366 }
1367
1368 /*
1369 * We must reset log_cnt when isInit or when changing any parameters that
1370 * would affect future nextval allocations.
1371 */
1372 if (isInit)
1373 seqdataform->log_cnt = 0;
1374
1375 /* AS type */
1376 if (as_type != NULL)
1377 {
1378 Oid newtypid = typenameTypeId(pstate, defGetTypeName(as_type));
1379
1380 if (newtypid != INT2OID &&
1381 newtypid != INT4OID &&
1382 newtypid != INT8OID)
1383 ereport(ERROR,
1384 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1385 for_identity
1386 ? errmsg("identity column type must be smallint, integer, or bigint")
1387 : errmsg("sequence type must be smallint, integer, or bigint")));
1388
1389 if (!isInit)
1390 {
1391 /*
1392 * When changing type and the old sequence min/max values were the
1393 * min/max of the old type, adjust sequence min/max values to
1394 * min/max of new type. (Otherwise, the user chose explicit
1395 * min/max values, which we'll leave alone.)
1396 */
1397 if ((seqform->seqtypid == INT2OID && seqform->seqmax == PG_INT16_MAX) ||
1398 (seqform->seqtypid == INT4OID && seqform->seqmax == PG_INT32_MAX) ||
1399 (seqform->seqtypid == INT8OID && seqform->seqmax == PG_INT64_MAX))
1400 reset_max_value = true;
1401 if ((seqform->seqtypid == INT2OID && seqform->seqmin == PG_INT16_MIN) ||
1402 (seqform->seqtypid == INT4OID && seqform->seqmin == PG_INT32_MIN) ||
1403 (seqform->seqtypid == INT8OID && seqform->seqmin == PG_INT64_MIN))
1404 reset_min_value = true;
1405 }
1406
1407 seqform->seqtypid = newtypid;
1408 }
1409 else if (isInit)
1410 {
1411 seqform->seqtypid = INT8OID;
1412 }
1413
1414 /* INCREMENT BY */
1415 if (increment_by != NULL)
1416 {
1417 seqform->seqincrement = defGetInt64(increment_by);
1418 if (seqform->seqincrement == 0)
1419 ereport(ERROR,
1420 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1421 errmsg("INCREMENT must not be zero")));
1422 seqdataform->log_cnt = 0;
1423 }
1424 else if (isInit)
1425 {
1426 seqform->seqincrement = 1;
1427 }
1428
1429 /* CYCLE */
1430 if (is_cycled != NULL)
1431 {
1432 seqform->seqcycle = intVal(is_cycled->arg);
1433 Assert(BoolIsValid(seqform->seqcycle));
1434 seqdataform->log_cnt = 0;
1435 }
1436 else if (isInit)
1437 {
1438 seqform->seqcycle = false;
1439 }
1440
1441 /* MAXVALUE (null arg means NO MAXVALUE) */
1442 if (max_value != NULL && max_value->arg)
1443 {
1444 seqform->seqmax = defGetInt64(max_value);
1445 seqdataform->log_cnt = 0;
1446 }
1447 else if (isInit || max_value != NULL || reset_max_value)
1448 {
1449 if (seqform->seqincrement > 0 || reset_max_value)
1450 {
1451 /* ascending seq */
1452 if (seqform->seqtypid == INT2OID)
1453 seqform->seqmax = PG_INT16_MAX;
1454 else if (seqform->seqtypid == INT4OID)
1455 seqform->seqmax = PG_INT32_MAX;
1456 else
1457 seqform->seqmax = PG_INT64_MAX;
1458 }
1459 else
1460 seqform->seqmax = -1; /* descending seq */
1461 seqdataform->log_cnt = 0;
1462 }
1463
1464 if ((seqform->seqtypid == INT2OID && (seqform->seqmax < PG_INT16_MIN || seqform->seqmax > PG_INT16_MAX))
1465 || (seqform->seqtypid == INT4OID && (seqform->seqmax < PG_INT32_MIN || seqform->seqmax > PG_INT32_MAX))
1466 || (seqform->seqtypid == INT8OID && (seqform->seqmax < PG_INT64_MIN || seqform->seqmax > PG_INT64_MAX)))
1467 {
1468 char bufx[100];
1469
1470 snprintf(bufx, sizeof(bufx), INT64_FORMAT, seqform->seqmax);
1471
1472 ereport(ERROR,
1473 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1474 errmsg("MAXVALUE (%s) is out of range for sequence data type %s",
1475 bufx, format_type_be(seqform->seqtypid))));
1476 }
1477
1478 /* MINVALUE (null arg means NO MINVALUE) */
1479 if (min_value != NULL && min_value->arg)
1480 {
1481 seqform->seqmin = defGetInt64(min_value);
1482 seqdataform->log_cnt = 0;
1483 }
1484 else if (isInit || min_value != NULL || reset_min_value)
1485 {
1486 if (seqform->seqincrement < 0 || reset_min_value)
1487 {
1488 /* descending seq */
1489 if (seqform->seqtypid == INT2OID)
1490 seqform->seqmin = PG_INT16_MIN;
1491 else if (seqform->seqtypid == INT4OID)
1492 seqform->seqmin = PG_INT32_MIN;
1493 else
1494 seqform->seqmin = PG_INT64_MIN;
1495 }
1496 else
1497 seqform->seqmin = 1; /* ascending seq */
1498 seqdataform->log_cnt = 0;
1499 }
1500
1501 if ((seqform->seqtypid == INT2OID && (seqform->seqmin < PG_INT16_MIN || seqform->seqmin > PG_INT16_MAX))
1502 || (seqform->seqtypid == INT4OID && (seqform->seqmin < PG_INT32_MIN || seqform->seqmin > PG_INT32_MAX))
1503 || (seqform->seqtypid == INT8OID && (seqform->seqmin < PG_INT64_MIN || seqform->seqmin > PG_INT64_MAX)))
1504 {
1505 char bufm[100];
1506
1507 snprintf(bufm, sizeof(bufm), INT64_FORMAT, seqform->seqmin);
1508
1509 ereport(ERROR,
1510 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1511 errmsg("MINVALUE (%s) is out of range for sequence data type %s",
1512 bufm, format_type_be(seqform->seqtypid))));
1513 }
1514
1515 /* crosscheck min/max */
1516 if (seqform->seqmin >= seqform->seqmax)
1517 {
1518 char bufm[100],
1519 bufx[100];
1520
1521 snprintf(bufm, sizeof(bufm), INT64_FORMAT, seqform->seqmin);
1522 snprintf(bufx, sizeof(bufx), INT64_FORMAT, seqform->seqmax);
1523 ereport(ERROR,
1524 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1525 errmsg("MINVALUE (%s) must be less than MAXVALUE (%s)",
1526 bufm, bufx)));
1527 }
1528
1529 /* START WITH */
1530 if (start_value != NULL)
1531 {
1532 seqform->seqstart = defGetInt64(start_value);
1533 }
1534 else if (isInit)
1535 {
1536 if (seqform->seqincrement > 0)
1537 seqform->seqstart = seqform->seqmin; /* ascending seq */
1538 else
1539 seqform->seqstart = seqform->seqmax; /* descending seq */
1540 }
1541
1542 /* crosscheck START */
1543 if (seqform->seqstart < seqform->seqmin)
1544 {
1545 char bufs[100],
1546 bufm[100];
1547
1548 snprintf(bufs, sizeof(bufs), INT64_FORMAT, seqform->seqstart);
1549 snprintf(bufm, sizeof(bufm), INT64_FORMAT, seqform->seqmin);
1550 ereport(ERROR,
1551 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1552 errmsg("START value (%s) cannot be less than MINVALUE (%s)",
1553 bufs, bufm)));
1554 }
1555 if (seqform->seqstart > seqform->seqmax)
1556 {
1557 char bufs[100],
1558 bufm[100];
1559
1560 snprintf(bufs, sizeof(bufs), INT64_FORMAT, seqform->seqstart);
1561 snprintf(bufm, sizeof(bufm), INT64_FORMAT, seqform->seqmax);
1562 ereport(ERROR,
1563 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1564 errmsg("START value (%s) cannot be greater than MAXVALUE (%s)",
1565 bufs, bufm)));
1566 }
1567
1568 /* RESTART [WITH] */
1569 if (restart_value != NULL)
1570 {
1571 if (restart_value->arg != NULL)
1572 seqdataform->last_value = defGetInt64(restart_value);
1573 else
1574 seqdataform->last_value = seqform->seqstart;
1575 seqdataform->is_called = false;
1576 seqdataform->log_cnt = 0;
1577 }
1578 else if (isInit)
1579 {
1580 seqdataform->last_value = seqform->seqstart;
1581 seqdataform->is_called = false;
1582 }
1583
1584 /* crosscheck RESTART (or current value, if changing MIN/MAX) */
1585 if (seqdataform->last_value < seqform->seqmin)
1586 {
1587 char bufs[100],
1588 bufm[100];
1589
1590 snprintf(bufs, sizeof(bufs), INT64_FORMAT, seqdataform->last_value);
1591 snprintf(bufm, sizeof(bufm), INT64_FORMAT, seqform->seqmin);
1592 ereport(ERROR,
1593 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1594 errmsg("RESTART value (%s) cannot be less than MINVALUE (%s)",
1595 bufs, bufm)));
1596 }
1597 if (seqdataform->last_value > seqform->seqmax)
1598 {
1599 char bufs[100],
1600 bufm[100];
1601
1602 snprintf(bufs, sizeof(bufs), INT64_FORMAT, seqdataform->last_value);
1603 snprintf(bufm, sizeof(bufm), INT64_FORMAT, seqform->seqmax);
1604 ereport(ERROR,
1605 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1606 errmsg("RESTART value (%s) cannot be greater than MAXVALUE (%s)",
1607 bufs, bufm)));
1608 }
1609
1610 /* CACHE */
1611 if (cache_value != NULL)
1612 {
1613 seqform->seqcache = defGetInt64(cache_value);
1614 if (seqform->seqcache <= 0)
1615 {
1616 char buf[100];
1617
1618 snprintf(buf, sizeof(buf), INT64_FORMAT, seqform->seqcache);
1619 ereport(ERROR,
1620 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1621 errmsg("CACHE (%s) must be greater than zero",
1622 buf)));
1623 }
1624 seqdataform->log_cnt = 0;
1625 }
1626 else if (isInit)
1627 {
1628 seqform->seqcache = 1;
1629 }
1630 }
1631
1632 /*
1633 * Process an OWNED BY option for CREATE/ALTER SEQUENCE
1634 *
1635 * Ownership permissions on the sequence are already checked,
1636 * but if we are establishing a new owned-by dependency, we must
1637 * enforce that the referenced table has the same owner and namespace
1638 * as the sequence.
1639 */
1640 static void
1641 process_owned_by(Relation seqrel, List *owned_by, bool for_identity)
1642 {
1643 DependencyType deptype;
1644 int nnames;
1645 Relation tablerel;
1646 AttrNumber attnum;
1647
1648 deptype = for_identity ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO;
1649
1650 nnames = list_length(owned_by);
1651 Assert(nnames > 0);
1652 if (nnames == 1)
1653 {
1654 /* Must be OWNED BY NONE */
1655 if (strcmp(strVal(linitial(owned_by)), "none") != 0)
1656 ereport(ERROR,
1657 (errcode(ERRCODE_SYNTAX_ERROR),
1658 errmsg("invalid OWNED BY option"),
1659 errhint("Specify OWNED BY table.column or OWNED BY NONE.")));
1660 tablerel = NULL;
1661 attnum = 0;
1662 }
1663 else
1664 {
1665 List *relname;
1666 char *attrname;
1667 RangeVar *rel;
1668
1669 /* Separate relname and attr name */
1670 relname = list_truncate(list_copy(owned_by), nnames - 1);
1671 attrname = strVal(lfirst(list_tail(owned_by)));
1672
1673 /* Open and lock rel to ensure it won't go away meanwhile */
1674 rel = makeRangeVarFromNameList(relname);
1675 tablerel = relation_openrv(rel, AccessShareLock);
1676
1677 /* Must be a regular or foreign table */
1678 if (!(tablerel->rd_rel->relkind == RELKIND_RELATION ||
1679 tablerel->rd_rel->relkind == RELKIND_FOREIGN_TABLE ||
1680 tablerel->rd_rel->relkind == RELKIND_VIEW ||
1681 tablerel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE))
1682 ereport(ERROR,
1683 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
1684 errmsg("referenced relation \"%s\" is not a table or foreign table",
1685 RelationGetRelationName(tablerel))));
1686
1687 /* We insist on same owner and schema */
1688 if (seqrel->rd_rel->relowner != tablerel->rd_rel->relowner)
1689 ereport(ERROR,
1690 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1691 errmsg("sequence must have same owner as table it is linked to")));
1692 if (RelationGetNamespace(seqrel) != RelationGetNamespace(tablerel))
1693 ereport(ERROR,
1694 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1695 errmsg("sequence must be in same schema as table it is linked to")));
1696
1697 /* Now, fetch the attribute number from the system cache */
1698 attnum = get_attnum(RelationGetRelid(tablerel), attrname);
1699 if (attnum == InvalidAttrNumber)
1700 ereport(ERROR,
1701 (errcode(ERRCODE_UNDEFINED_COLUMN),
1702 errmsg("column \"%s\" of relation \"%s\" does not exist",
1703 attrname, RelationGetRelationName(tablerel))));
1704 }
1705
1706 /*
1707 * Catch user explicitly running OWNED BY on identity sequence.
1708 */
1709 if (deptype == DEPENDENCY_AUTO)
1710 {
1711 Oid tableId;
1712 int32 colId;
1713
1714 if (sequenceIsOwned(RelationGetRelid(seqrel), DEPENDENCY_INTERNAL, &tableId, &colId))
1715 ereport(ERROR,
1716 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1717 errmsg("cannot change ownership of identity sequence"),
1718 errdetail("Sequence \"%s\" is linked to table \"%s\".",
1719 RelationGetRelationName(seqrel),
1720 get_rel_name(tableId))));
1721 }
1722
1723 /*
1724 * OK, we are ready to update pg_depend. First remove any existing
1725 * dependencies for the sequence, then optionally add a new one.
1726 */
1727 deleteDependencyRecordsForClass(RelationRelationId, RelationGetRelid(seqrel),
1728 RelationRelationId, deptype);
1729
1730 if (tablerel)
1731 {
1732 ObjectAddress refobject,
1733 depobject;
1734
1735 refobject.classId = RelationRelationId;
1736 refobject.objectId = RelationGetRelid(tablerel);
1737 refobject.objectSubId = attnum;
1738 depobject.classId = RelationRelationId;
1739 depobject.objectId = RelationGetRelid(seqrel);
1740 depobject.objectSubId = 0;
1741 recordDependencyOn(&depobject, &refobject, deptype);
1742 }
1743
1744 /* Done, but hold lock until commit */
1745 if (tablerel)
1746 relation_close(tablerel, NoLock);
1747 }
1748
1749
1750 /*
1751 * Return sequence parameters in a list of the form created by the parser.
1752 */
1753 List *
1754 sequence_options(Oid relid)
1755 {
1756 HeapTuple pgstuple;
1757 Form_pg_sequence pgsform;
1758 List *options = NIL;
1759
1760 pgstuple = SearchSysCache1(SEQRELID, relid);
1761 if (!HeapTupleIsValid(pgstuple))
1762 elog(ERROR, "cache lookup failed for sequence %u", relid);
1763 pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
1764
1765 /* Use makeFloat() for 64-bit integers, like gram.y does. */
1766 options = lappend(options,
1767 makeDefElem("cache", (Node *) makeFloat(psprintf(INT64_FORMAT, pgsform->seqcache)), -1));
1768 options = lappend(options,
1769 makeDefElem("cycle", (Node *) makeInteger(pgsform->seqcycle), -1));
1770 options = lappend(options,
1771 makeDefElem("increment", (Node *) makeFloat(psprintf(INT64_FORMAT, pgsform->seqincrement)), -1));
1772 options = lappend(options,
1773 makeDefElem("maxvalue", (Node *) makeFloat(psprintf(INT64_FORMAT, pgsform->seqmax)), -1));
1774 options = lappend(options,
1775 makeDefElem("minvalue", (Node *) makeFloat(psprintf(INT64_FORMAT, pgsform->seqmin)), -1));
1776 options = lappend(options,
1777 makeDefElem("start", (Node *) makeFloat(psprintf(INT64_FORMAT, pgsform->seqstart)), -1));
1778
1779 ReleaseSysCache(pgstuple);
1780
1781 return options;
1782 }
1783
1784 /*
1785 * Return sequence parameters (formerly for use by information schema)
1786 */
1787 Datum
1788 pg_sequence_parameters(PG_FUNCTION_ARGS)
1789 {
1790 Oid relid = PG_GETARG_OID(0);
1791 TupleDesc tupdesc;
1792 Datum values[7];
1793 bool isnull[7];
1794 HeapTuple pgstuple;
1795 Form_pg_sequence pgsform;
1796
1797 if (pg_class_aclcheck(relid, GetUserId(), ACL_SELECT | ACL_UPDATE | ACL_USAGE) != ACLCHECK_OK)
1798 ereport(ERROR,
1799 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
1800 errmsg("permission denied for sequence %s",
1801 get_rel_name(relid))));
1802
1803 tupdesc = CreateTemplateTupleDesc(7);
1804 TupleDescInitEntry(tupdesc, (AttrNumber) 1, "start_value",
1805 INT8OID, -1, 0);
1806 TupleDescInitEntry(tupdesc, (AttrNumber) 2, "minimum_value",
1807 INT8OID, -1, 0);
1808 TupleDescInitEntry(tupdesc, (AttrNumber) 3, "maximum_value",
1809 INT8OID, -1, 0);
1810 TupleDescInitEntry(tupdesc, (AttrNumber) 4, "increment",
1811 INT8OID, -1, 0);
1812 TupleDescInitEntry(tupdesc, (AttrNumber) 5, "cycle_option",
1813 BOOLOID, -1, 0);
1814 TupleDescInitEntry(tupdesc, (AttrNumber) 6, "cache_size",
1815 INT8OID, -1, 0);
1816 TupleDescInitEntry(tupdesc, (AttrNumber) 7, "data_type",
1817 OIDOID, -1, 0);
1818
1819 BlessTupleDesc(tupdesc);
1820
1821 memset(isnull, 0, sizeof(isnull));
1822
1823 pgstuple = SearchSysCache1(SEQRELID, relid);
1824 if (!HeapTupleIsValid(pgstuple))
1825 elog(ERROR, "cache lookup failed for sequence %u", relid);
1826 pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
1827
1828 values[0] = Int64GetDatum(pgsform->seqstart);
1829 values[1] = Int64GetDatum(pgsform->seqmin);
1830 values[2] = Int64GetDatum(pgsform->seqmax);
1831 values[3] = Int64GetDatum(pgsform->seqincrement);
1832 values[4] = BoolGetDatum(pgsform->seqcycle);
1833 values[5] = Int64GetDatum(pgsform->seqcache);
1834 values[6] = ObjectIdGetDatum(pgsform->seqtypid);
1835
1836 ReleaseSysCache(pgstuple);
1837
1838 return HeapTupleGetDatum(heap_form_tuple(tupdesc, values, isnull));
1839 }
1840
1841 /*
1842 * Return the last value from the sequence
1843 *
1844 * Note: This has a completely different meaning than lastval().
1845 */
1846 Datum
1847 pg_sequence_last_value(PG_FUNCTION_ARGS)
1848 {
1849 Oid relid = PG_GETARG_OID(0);
1850 SeqTable elm;
1851 Relation seqrel;
1852 Buffer buf;
1853 HeapTupleData seqtuple;
1854 Form_pg_sequence_data seq;
1855 bool is_called;
1856 int64 result;
1857
1858 /* open and lock sequence */
1859 init_sequence(relid, &elm, &seqrel);
1860
1861 if (pg_class_aclcheck(relid, GetUserId(), ACL_SELECT | ACL_USAGE) != ACLCHECK_OK)
1862 ereport(ERROR,
1863 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
1864 errmsg("permission denied for sequence %s",
1865 RelationGetRelationName(seqrel))));
1866
1867 seq = read_seq_tuple(seqrel, &buf, &seqtuple);
1868
1869 is_called = seq->is_called;
1870 result = seq->last_value;
1871
1872 UnlockReleaseBuffer(buf);
1873 relation_close(seqrel, NoLock);
1874
1875 if (is_called)
1876 PG_RETURN_INT64(result);
1877 else
1878 PG_RETURN_NULL();
1879 }
1880
1881
1882 void
1883 seq_redo(XLogReaderState *record)
1884 {
1885 XLogRecPtr lsn = record->EndRecPtr;
1886 uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
1887 Buffer buffer;
1888 Page page;
1889 Page localpage;
1890 char *item;
1891 Size itemsz;
1892 xl_seq_rec *xlrec = (xl_seq_rec *) XLogRecGetData(record);
1893 sequence_magic *sm;
1894
1895 if (info != XLOG_SEQ_LOG)
1896 elog(PANIC, "seq_redo: unknown op code %u", info);
1897
1898 buffer = XLogInitBufferForRedo(record, 0);
1899 page = (Page) BufferGetPage(buffer);
1900
1901 /*
1902 * We always reinit the page. However, since this WAL record type is also
1903 * used for updating sequences, it's possible that a hot-standby backend
1904 * is examining the page concurrently; so we mustn't transiently trash the
1905 * buffer. The solution is to build the correct new page contents in
1906 * local workspace and then memcpy into the buffer. Then only bytes that
1907 * are supposed to change will change, even transiently. We must palloc
1908 * the local page for alignment reasons.
1909 */
1910 localpage = (Page) palloc(BufferGetPageSize(buffer));
1911
1912 PageInit(localpage, BufferGetPageSize(buffer), sizeof(sequence_magic));
1913 sm = (sequence_magic *) PageGetSpecialPointer(localpage);
1914 sm->magic = SEQ_MAGIC;
1915
1916 item = (char *) xlrec + sizeof(xl_seq_rec);
1917 itemsz = XLogRecGetDataLen(record) - sizeof(xl_seq_rec);
1918
1919 if (PageAddItem(localpage, (Item) item, itemsz,
1920 FirstOffsetNumber, false, false) == InvalidOffsetNumber)
1921 elog(PANIC, "seq_redo: failed to add item to page");
1922
1923 PageSetLSN(localpage, lsn);
1924
1925 memcpy(page, localpage, BufferGetPageSize(buffer));
1926 MarkBufferDirty(buffer);
1927 UnlockReleaseBuffer(buffer);
1928
1929 pfree(localpage);
1930 }
1931
1932 /*
1933 * Flush cached sequence information.
1934 */
1935 void
1936 ResetSequenceCaches(void)
1937 {
1938 if (seqhashtab)
1939 {
1940 hash_destroy(seqhashtab);
1941 seqhashtab = NULL;
1942 }
1943
1944 last_used_seq = NULL;
1945 }
1946
1947 /*
1948 * Mask a Sequence page before performing consistency checks on it.
1949 */
1950 void
1951 seq_mask(char *page, BlockNumber blkno)
1952 {
1953 mask_page_lsn_and_checksum(page);
1954
1955 mask_unused_space(page);
1956 }
1957