Line data Source code
1 : /*-------------------------------------------------------------------------
2 : * sequencesync.c
3 : * PostgreSQL logical replication: sequence synchronization
4 : *
5 : * Copyright (c) 2025-2026, PostgreSQL Global Development Group
6 : *
7 : * IDENTIFICATION
8 : * src/backend/replication/logical/sequencesync.c
9 : *
10 : * NOTES
11 : * This file contains code for sequence synchronization for
12 : * logical replication.
13 : *
14 : * Sequences requiring synchronization are tracked in the pg_subscription_rel
15 : * catalog.
16 : *
17 : * Sequences to be synchronized will be added with state INIT when either of
18 : * the following commands is executed:
19 : * CREATE SUBSCRIPTION
20 : * ALTER SUBSCRIPTION ... REFRESH PUBLICATION
21 : *
22 : * Executing the following command resets all sequences in the subscription to
23 : * state INIT, triggering re-synchronization:
24 : * ALTER SUBSCRIPTION ... REFRESH SEQUENCES
25 : *
26 : * The apply worker periodically scans pg_subscription_rel for sequences in
27 : * INIT state. When such sequences are found, it spawns a sequencesync worker
28 : * to handle synchronization.
29 : *
30 : * A single sequencesync worker is responsible for synchronizing all sequences.
31 : * It begins by retrieving the list of sequences that are flagged for
32 : * synchronization, i.e., those in the INIT state. These sequences are then
33 : * processed in batches, allowing multiple entries to be synchronized within a
34 : * single transaction. The worker fetches the current sequence values and page
35 : * LSNs from the remote publisher, updates the corresponding sequences on the
36 : * local subscriber, and finally marks each sequence as READY upon successful
37 : * synchronization.
38 : *
39 : * Sequence state transitions follow this pattern:
40 : * INIT -> READY
41 : *
42 : * To avoid creating too many transactions, up to MAX_SEQUENCES_SYNC_PER_BATCH
43 : * sequences are synchronized per transaction. The locks on the sequence
44 : * relation will be periodically released at each transaction commit.
45 : *
46 : * XXX: We didn't choose launcher process to maintain the launch of sequencesync
47 : * worker as it didn't have database connection to access the sequences from the
48 : * pg_subscription_rel system catalog that need to be synchronized.
49 : *-------------------------------------------------------------------------
50 : */
51 :
52 : #include "postgres.h"
53 :
54 : #include "access/genam.h"
55 : #include "access/table.h"
56 : #include "catalog/pg_sequence.h"
57 : #include "catalog/pg_subscription_rel.h"
58 : #include "commands/sequence.h"
59 : #include "pgstat.h"
60 : #include "postmaster/interrupt.h"
61 : #include "replication/logicalworker.h"
62 : #include "replication/worker_internal.h"
63 : #include "utils/acl.h"
64 : #include "utils/builtins.h"
65 : #include "utils/fmgroids.h"
66 : #include "utils/guc.h"
67 : #include "utils/inval.h"
68 : #include "utils/lsyscache.h"
69 : #include "utils/memutils.h"
70 : #include "utils/pg_lsn.h"
71 : #include "utils/syscache.h"
72 : #include "utils/usercontext.h"
73 :
74 : #define REMOTE_SEQ_COL_COUNT 10
75 :
76 : typedef enum CopySeqResult
77 : {
78 : COPYSEQ_SUCCESS,
79 : COPYSEQ_MISMATCH,
80 : COPYSEQ_INSUFFICIENT_PERM,
81 : COPYSEQ_SKIPPED
82 : } CopySeqResult;
83 :
84 : static List *seqinfos = NIL;
85 :
86 : /*
87 : * Apply worker determines if sequence synchronization is needed.
88 : *
89 : * Start a sequencesync worker if one is not already running. The active
90 : * sequencesync worker will handle all pending sequence synchronization. If any
91 : * sequences remain unsynchronized after it exits, a new worker can be started
92 : * in the next iteration.
93 : */
94 : void
95 10720 : ProcessSequencesForSync(void)
96 : {
97 : LogicalRepWorker *sequencesync_worker;
98 : int nsyncworkers;
99 : bool has_pending_sequences;
100 : bool started_tx;
101 :
102 10720 : FetchRelationStates(NULL, &has_pending_sequences, &started_tx);
103 :
104 10720 : if (started_tx)
105 : {
106 350 : CommitTransactionCommand();
107 350 : pgstat_report_stat(true);
108 : }
109 :
110 10720 : if (!has_pending_sequences)
111 10688 : return;
112 :
113 50 : LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
114 :
115 : /* Check if there is a sequencesync worker already running? */
116 50 : sequencesync_worker = logicalrep_worker_find(WORKERTYPE_SEQUENCESYNC,
117 50 : MyLogicalRepWorker->subid,
118 : InvalidOid, true);
119 50 : if (sequencesync_worker)
120 : {
121 18 : LWLockRelease(LogicalRepWorkerLock);
122 18 : return;
123 : }
124 :
125 : /*
126 : * Count running sync workers for this subscription, while we have the
127 : * lock.
128 : */
129 32 : nsyncworkers = logicalrep_sync_worker_count(MyLogicalRepWorker->subid);
130 32 : LWLockRelease(LogicalRepWorkerLock);
131 :
132 : /*
133 : * It is okay to read/update last_seqsync_start_time here in apply worker
134 : * as we have already ensured that sync worker doesn't exist.
135 : */
136 32 : launch_sync_worker(WORKERTYPE_SEQUENCESYNC, nsyncworkers, InvalidOid,
137 32 : &MyLogicalRepWorker->last_seqsync_start_time);
138 : }
139 :
140 : /*
141 : * get_sequences_string
142 : *
143 : * Build a comma-separated string of schema-qualified sequence names
144 : * for the given list of sequence indexes.
145 : */
146 : static void
147 8 : get_sequences_string(List *seqindexes, StringInfo buf)
148 : {
149 8 : resetStringInfo(buf);
150 24 : foreach_int(seqidx, seqindexes)
151 : {
152 : LogicalRepSequenceInfo *seqinfo =
153 8 : (LogicalRepSequenceInfo *) list_nth(seqinfos, seqidx);
154 :
155 8 : if (buf->len > 0)
156 0 : appendStringInfoString(buf, ", ");
157 :
158 8 : appendStringInfo(buf, "\"%s.%s\"", seqinfo->nspname, seqinfo->seqname);
159 : }
160 8 : }
161 :
162 : /*
163 : * report_sequence_errors
164 : *
165 : * Report discrepancies found during sequence synchronization between
166 : * the publisher and subscriber. Emits warnings for:
167 : * a) mismatched definitions or concurrent rename
168 : * b) insufficient privileges
169 : * c) missing sequences on the subscriber
170 : * Then raises an ERROR to indicate synchronization failure.
171 : */
172 : static void
173 18 : report_sequence_errors(List *mismatched_seqs_idx, List *insuffperm_seqs_idx,
174 : List *missing_seqs_idx)
175 : {
176 : StringInfo seqstr;
177 :
178 : /* Quick exit if there are no errors to report */
179 18 : if (!mismatched_seqs_idx && !insuffperm_seqs_idx && !missing_seqs_idx)
180 10 : return;
181 :
182 8 : seqstr = makeStringInfo();
183 :
184 8 : if (mismatched_seqs_idx)
185 : {
186 6 : get_sequences_string(mismatched_seqs_idx, seqstr);
187 6 : ereport(WARNING,
188 : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
189 : errmsg_plural("mismatched or renamed sequence on subscriber (%s)",
190 : "mismatched or renamed sequences on subscriber (%s)",
191 : list_length(mismatched_seqs_idx),
192 : seqstr->data));
193 : }
194 :
195 8 : if (insuffperm_seqs_idx)
196 : {
197 0 : get_sequences_string(insuffperm_seqs_idx, seqstr);
198 0 : ereport(WARNING,
199 : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
200 : errmsg_plural("insufficient privileges on sequence (%s)",
201 : "insufficient privileges on sequences (%s)",
202 : list_length(insuffperm_seqs_idx),
203 : seqstr->data));
204 : }
205 :
206 8 : if (missing_seqs_idx)
207 : {
208 2 : get_sequences_string(missing_seqs_idx, seqstr);
209 2 : ereport(WARNING,
210 : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
211 : errmsg_plural("missing sequence on publisher (%s)",
212 : "missing sequences on publisher (%s)",
213 : list_length(missing_seqs_idx),
214 : seqstr->data));
215 : }
216 :
217 8 : ereport(ERROR,
218 : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
219 : errmsg("logical replication sequence synchronization failed for subscription \"%s\"",
220 : MySubscription->name));
221 : }
222 :
223 : /*
224 : * get_and_validate_seq_info
225 : *
226 : * Extracts remote sequence information from the tuple slot received from the
227 : * publisher, and validates it against the corresponding local sequence
228 : * definition.
229 : */
230 : static CopySeqResult
231 24 : get_and_validate_seq_info(TupleTableSlot *slot, Relation *sequence_rel,
232 : LogicalRepSequenceInfo **seqinfo, int *seqidx)
233 : {
234 : bool isnull;
235 24 : int col = 0;
236 : Datum datum;
237 : Oid remote_typid;
238 : int64 remote_start;
239 : int64 remote_increment;
240 : int64 remote_min;
241 : int64 remote_max;
242 : bool remote_cycle;
243 24 : CopySeqResult result = COPYSEQ_SUCCESS;
244 : HeapTuple tup;
245 : Form_pg_sequence local_seq;
246 : LogicalRepSequenceInfo *seqinfo_local;
247 :
248 24 : *seqidx = DatumGetInt32(slot_getattr(slot, ++col, &isnull));
249 : Assert(!isnull);
250 :
251 : /* Identify the corresponding local sequence for the given index. */
252 24 : *seqinfo = seqinfo_local =
253 24 : (LogicalRepSequenceInfo *) list_nth(seqinfos, *seqidx);
254 :
255 : /*
256 : * last_value can be NULL if the sequence was dropped concurrently (see
257 : * pg_get_sequence_data()).
258 : */
259 24 : datum = slot_getattr(slot, ++col, &isnull);
260 24 : if (isnull)
261 0 : return COPYSEQ_SKIPPED;
262 24 : seqinfo_local->last_value = DatumGetInt64(datum);
263 :
264 24 : seqinfo_local->is_called = DatumGetBool(slot_getattr(slot, ++col, &isnull));
265 : Assert(!isnull);
266 :
267 24 : seqinfo_local->page_lsn = DatumGetLSN(slot_getattr(slot, ++col, &isnull));
268 : Assert(!isnull);
269 :
270 24 : remote_typid = DatumGetObjectId(slot_getattr(slot, ++col, &isnull));
271 : Assert(!isnull);
272 :
273 24 : remote_start = DatumGetInt64(slot_getattr(slot, ++col, &isnull));
274 : Assert(!isnull);
275 :
276 24 : remote_increment = DatumGetInt64(slot_getattr(slot, ++col, &isnull));
277 : Assert(!isnull);
278 :
279 24 : remote_min = DatumGetInt64(slot_getattr(slot, ++col, &isnull));
280 : Assert(!isnull);
281 :
282 24 : remote_max = DatumGetInt64(slot_getattr(slot, ++col, &isnull));
283 : Assert(!isnull);
284 :
285 24 : remote_cycle = DatumGetBool(slot_getattr(slot, ++col, &isnull));
286 : Assert(!isnull);
287 :
288 : /* Sanity check */
289 : Assert(col == REMOTE_SEQ_COL_COUNT);
290 :
291 24 : seqinfo_local->found_on_pub = true;
292 :
293 24 : *sequence_rel = try_table_open(seqinfo_local->localrelid, RowExclusiveLock);
294 :
295 : /* Sequence was concurrently dropped? */
296 24 : if (!*sequence_rel)
297 0 : return COPYSEQ_SKIPPED;
298 :
299 24 : tup = SearchSysCache1(SEQRELID, ObjectIdGetDatum(seqinfo_local->localrelid));
300 :
301 : /* Sequence was concurrently dropped? */
302 24 : if (!HeapTupleIsValid(tup))
303 0 : elog(ERROR, "cache lookup failed for sequence %u",
304 : seqinfo_local->localrelid);
305 :
306 24 : local_seq = (Form_pg_sequence) GETSTRUCT(tup);
307 :
308 : /* Sequence parameters for remote/local are the same? */
309 24 : if (local_seq->seqtypid != remote_typid ||
310 24 : local_seq->seqstart != remote_start ||
311 22 : local_seq->seqincrement != remote_increment ||
312 18 : local_seq->seqmin != remote_min ||
313 18 : local_seq->seqmax != remote_max ||
314 18 : local_seq->seqcycle != remote_cycle)
315 6 : result = COPYSEQ_MISMATCH;
316 :
317 : /* Sequence was concurrently renamed? */
318 24 : if (strcmp(seqinfo_local->nspname,
319 24 : get_namespace_name(RelationGetNamespace(*sequence_rel))) ||
320 24 : strcmp(seqinfo_local->seqname, RelationGetRelationName(*sequence_rel)))
321 0 : result = COPYSEQ_MISMATCH;
322 :
323 24 : ReleaseSysCache(tup);
324 24 : return result;
325 : }
326 :
327 : /*
328 : * Apply remote sequence state to local sequence and mark it as
329 : * synchronized (READY).
330 : */
331 : static CopySeqResult
332 18 : copy_sequence(LogicalRepSequenceInfo *seqinfo, Oid seqowner)
333 : {
334 : UserContext ucxt;
335 : AclResult aclresult;
336 18 : bool run_as_owner = MySubscription->runasowner;
337 18 : Oid seqoid = seqinfo->localrelid;
338 :
339 : /*
340 : * If the user did not opt to run as the owner of the subscription
341 : * ('run_as_owner'), then copy the sequence as the owner of the sequence.
342 : */
343 18 : if (!run_as_owner)
344 18 : SwitchToUntrustedUser(seqowner, &ucxt);
345 :
346 18 : aclresult = pg_class_aclcheck(seqoid, GetUserId(), ACL_UPDATE);
347 :
348 18 : if (aclresult != ACLCHECK_OK)
349 : {
350 0 : if (!run_as_owner)
351 0 : RestoreUserContext(&ucxt);
352 :
353 0 : return COPYSEQ_INSUFFICIENT_PERM;
354 : }
355 :
356 : /*
357 : * The log counter (log_cnt) tracks how many sequence values are still
358 : * unused locally. It is only relevant to the local node and managed
359 : * internally by nextval() when allocating new ranges. Since log_cnt does
360 : * not affect the visible sequence state (like last_value or is_called)
361 : * and is only used for local caching, it need not be copied to the
362 : * subscriber during synchronization.
363 : */
364 18 : SetSequence(seqoid, seqinfo->last_value, seqinfo->is_called);
365 :
366 18 : if (!run_as_owner)
367 18 : RestoreUserContext(&ucxt);
368 :
369 : /*
370 : * Record the remote sequence's LSN in pg_subscription_rel and mark the
371 : * sequence as READY.
372 : */
373 18 : UpdateSubscriptionRelState(MySubscription->oid, seqoid, SUBREL_STATE_READY,
374 : seqinfo->page_lsn, false);
375 :
376 18 : return COPYSEQ_SUCCESS;
377 : }
378 :
379 : /*
380 : * Copy existing data of sequences from the publisher.
381 : */
382 : static void
383 18 : copy_sequences(WalReceiverConn *conn)
384 : {
385 18 : int cur_batch_base_index = 0;
386 18 : int n_seqinfos = list_length(seqinfos);
387 18 : List *mismatched_seqs_idx = NIL;
388 18 : List *missing_seqs_idx = NIL;
389 18 : List *insuffperm_seqs_idx = NIL;
390 18 : StringInfo seqstr = makeStringInfo();
391 18 : StringInfo cmd = makeStringInfo();
392 : MemoryContext oldctx;
393 :
394 : #define MAX_SEQUENCES_SYNC_PER_BATCH 100
395 :
396 18 : elog(DEBUG1,
397 : "logical replication sequence synchronization for subscription \"%s\" - total unsynchronized: %d",
398 : MySubscription->name, n_seqinfos);
399 :
400 36 : while (cur_batch_base_index < n_seqinfos)
401 : {
402 18 : Oid seqRow[REMOTE_SEQ_COL_COUNT] = {INT8OID, INT8OID,
403 : BOOLOID, LSNOID, OIDOID, INT8OID, INT8OID, INT8OID, INT8OID, BOOLOID};
404 18 : int batch_size = 0;
405 18 : int batch_succeeded_count = 0;
406 18 : int batch_mismatched_count = 0;
407 18 : int batch_skipped_count = 0;
408 18 : int batch_insuffperm_count = 0;
409 : int batch_missing_count;
410 18 : Relation sequence_rel = NULL;
411 :
412 : WalRcvExecResult *res;
413 : TupleTableSlot *slot;
414 :
415 18 : StartTransactionCommand();
416 :
417 44 : for (int idx = cur_batch_base_index; idx < n_seqinfos; idx++)
418 : {
419 : char *nspname_literal;
420 : char *seqname_literal;
421 :
422 : LogicalRepSequenceInfo *seqinfo =
423 26 : (LogicalRepSequenceInfo *) list_nth(seqinfos, idx);
424 :
425 26 : if (seqstr->len > 0)
426 8 : appendStringInfoString(seqstr, ", ");
427 :
428 26 : nspname_literal = quote_literal_cstr(seqinfo->nspname);
429 26 : seqname_literal = quote_literal_cstr(seqinfo->seqname);
430 :
431 26 : appendStringInfo(seqstr, "(%s, %s, %d)",
432 : nspname_literal, seqname_literal, idx);
433 :
434 26 : if (++batch_size == MAX_SEQUENCES_SYNC_PER_BATCH)
435 0 : break;
436 : }
437 :
438 : /*
439 : * We deliberately avoid acquiring a local lock on the sequence before
440 : * querying the publisher to prevent potential distributed deadlocks
441 : * in bi-directional replication setups.
442 : *
443 : * Example scenario:
444 : *
445 : * - On each node, a background worker acquires a lock on a sequence
446 : * as part of a sync operation.
447 : *
448 : * - Concurrently, a user transaction attempts to alter the same
449 : * sequence, waiting on the background worker's lock.
450 : *
451 : * - Meanwhile, a query from the other node tries to access metadata
452 : * that depends on the completion of the alter operation.
453 : *
454 : * - This creates a circular wait across nodes:
455 : *
456 : * Node-1: Query -> waits on Alter -> waits on Sync Worker
457 : *
458 : * Node-2: Query -> waits on Alter -> waits on Sync Worker
459 : *
460 : * Since each node only sees part of the wait graph, the deadlock may
461 : * go undetected, leading to indefinite blocking.
462 : *
463 : * Note: Each entry in VALUES includes an index 'seqidx' that
464 : * represents the sequence's position in the local 'seqinfos' list.
465 : * This index is propagated to the query results and later used to
466 : * directly map the fetched publisher sequence rows back to their
467 : * corresponding local entries without relying on result order or name
468 : * matching.
469 : */
470 18 : appendStringInfo(cmd,
471 : "SELECT s.seqidx, ps.*, seq.seqtypid,\n"
472 : " seq.seqstart, seq.seqincrement, seq.seqmin,\n"
473 : " seq.seqmax, seq.seqcycle\n"
474 : "FROM ( VALUES %s ) AS s (schname, seqname, seqidx)\n"
475 : "JOIN pg_namespace n ON n.nspname = s.schname\n"
476 : "JOIN pg_class c ON c.relnamespace = n.oid AND c.relname = s.seqname\n"
477 : "JOIN pg_sequence seq ON seq.seqrelid = c.oid\n"
478 : "JOIN LATERAL pg_get_sequence_data(seq.seqrelid) AS ps ON true\n",
479 : seqstr->data);
480 :
481 18 : res = walrcv_exec(conn, cmd->data, lengthof(seqRow), seqRow);
482 18 : if (res->status != WALRCV_OK_TUPLES)
483 0 : ereport(ERROR,
484 : errcode(ERRCODE_CONNECTION_FAILURE),
485 : errmsg("could not fetch sequence information from the publisher: %s",
486 : res->err));
487 :
488 18 : slot = MakeSingleTupleTableSlot(res->tupledesc, &TTSOpsMinimalTuple);
489 42 : while (tuplestore_gettupleslot(res->tuplestore, true, false, slot))
490 : {
491 : CopySeqResult sync_status;
492 : LogicalRepSequenceInfo *seqinfo;
493 : int seqidx;
494 :
495 24 : CHECK_FOR_INTERRUPTS();
496 :
497 24 : if (ConfigReloadPending)
498 : {
499 0 : ConfigReloadPending = false;
500 0 : ProcessConfigFile(PGC_SIGHUP);
501 : }
502 :
503 24 : sync_status = get_and_validate_seq_info(slot, &sequence_rel,
504 : &seqinfo, &seqidx);
505 24 : if (sync_status == COPYSEQ_SUCCESS)
506 18 : sync_status = copy_sequence(seqinfo,
507 18 : sequence_rel->rd_rel->relowner);
508 :
509 24 : switch (sync_status)
510 : {
511 18 : case COPYSEQ_SUCCESS:
512 18 : elog(DEBUG1,
513 : "logical replication synchronization for subscription \"%s\", sequence \"%s.%s\" has finished",
514 : MySubscription->name, seqinfo->nspname,
515 : seqinfo->seqname);
516 18 : batch_succeeded_count++;
517 18 : break;
518 6 : case COPYSEQ_MISMATCH:
519 :
520 : /*
521 : * Remember mismatched sequences in a long-lived memory
522 : * context since these will be used after the transaction
523 : * is committed.
524 : */
525 6 : oldctx = MemoryContextSwitchTo(ApplyContext);
526 6 : mismatched_seqs_idx = lappend_int(mismatched_seqs_idx,
527 : seqidx);
528 6 : MemoryContextSwitchTo(oldctx);
529 6 : batch_mismatched_count++;
530 6 : break;
531 0 : case COPYSEQ_INSUFFICIENT_PERM:
532 :
533 : /*
534 : * Remember sequences with insufficient privileges in a
535 : * long-lived memory context since these will be used
536 : * after the transaction is committed.
537 : */
538 0 : oldctx = MemoryContextSwitchTo(ApplyContext);
539 0 : insuffperm_seqs_idx = lappend_int(insuffperm_seqs_idx,
540 : seqidx);
541 0 : MemoryContextSwitchTo(oldctx);
542 0 : batch_insuffperm_count++;
543 0 : break;
544 0 : case COPYSEQ_SKIPPED:
545 :
546 : /*
547 : * Concurrent removal of a sequence on the subscriber is
548 : * treated as success, since the only viable action is to
549 : * skip the corresponding sequence data. Missing sequences
550 : * on the publisher are treated as ERROR.
551 : */
552 0 : if (seqinfo->found_on_pub)
553 : {
554 0 : ereport(LOG,
555 : errmsg("skip synchronization of sequence \"%s.%s\" because it has been dropped concurrently",
556 : seqinfo->nspname,
557 : seqinfo->seqname));
558 0 : batch_skipped_count++;
559 : }
560 0 : break;
561 : }
562 :
563 24 : if (sequence_rel)
564 24 : table_close(sequence_rel, NoLock);
565 : }
566 :
567 18 : ExecDropSingleTupleTableSlot(slot);
568 18 : walrcv_clear_result(res);
569 18 : resetStringInfo(seqstr);
570 18 : resetStringInfo(cmd);
571 :
572 18 : batch_missing_count = batch_size - (batch_succeeded_count +
573 18 : batch_mismatched_count +
574 18 : batch_insuffperm_count +
575 : batch_skipped_count);
576 :
577 18 : elog(DEBUG1,
578 : "logical replication sequence synchronization for subscription \"%s\" - batch #%d = %d attempted, %d succeeded, %d mismatched, %d insufficient permission, %d missing from publisher, %d skipped",
579 : MySubscription->name,
580 : (cur_batch_base_index / MAX_SEQUENCES_SYNC_PER_BATCH) + 1,
581 : batch_size, batch_succeeded_count, batch_mismatched_count,
582 : batch_insuffperm_count, batch_missing_count, batch_skipped_count);
583 :
584 : /* Commit this batch, and prepare for next batch */
585 18 : CommitTransactionCommand();
586 :
587 18 : if (batch_missing_count)
588 : {
589 4 : for (int idx = cur_batch_base_index; idx < cur_batch_base_index + batch_size; idx++)
590 : {
591 : LogicalRepSequenceInfo *seqinfo =
592 2 : (LogicalRepSequenceInfo *) list_nth(seqinfos, idx);
593 :
594 : /* If the sequence was not found on publisher, record it */
595 2 : if (!seqinfo->found_on_pub)
596 2 : missing_seqs_idx = lappend_int(missing_seqs_idx, idx);
597 : }
598 : }
599 :
600 : /*
601 : * cur_batch_base_index is not incremented sequentially because some
602 : * sequences may be missing, and the number of fetched rows may not
603 : * match the batch size.
604 : */
605 18 : cur_batch_base_index += batch_size;
606 : }
607 :
608 : /* Report mismatches, permission issues, or missing sequences */
609 18 : report_sequence_errors(mismatched_seqs_idx, insuffperm_seqs_idx,
610 : missing_seqs_idx);
611 10 : }
612 :
613 : /*
614 : * Identifies sequences that require synchronization and initiates the
615 : * synchronization process.
616 : */
617 : static void
618 18 : LogicalRepSyncSequences(void)
619 : {
620 : char *err;
621 : bool must_use_password;
622 : Relation rel;
623 : HeapTuple tup;
624 : ScanKeyData skey[2];
625 : SysScanDesc scan;
626 18 : Oid subid = MyLogicalRepWorker->subid;
627 : StringInfoData app_name;
628 :
629 18 : StartTransactionCommand();
630 :
631 18 : rel = table_open(SubscriptionRelRelationId, AccessShareLock);
632 :
633 18 : ScanKeyInit(&skey[0],
634 : Anum_pg_subscription_rel_srsubid,
635 : BTEqualStrategyNumber, F_OIDEQ,
636 : ObjectIdGetDatum(subid));
637 :
638 18 : ScanKeyInit(&skey[1],
639 : Anum_pg_subscription_rel_srsubstate,
640 : BTEqualStrategyNumber, F_CHAREQ,
641 : CharGetDatum(SUBREL_STATE_INIT));
642 :
643 18 : scan = systable_beginscan(rel, InvalidOid, false,
644 : NULL, 2, skey);
645 44 : while (HeapTupleIsValid(tup = systable_getnext(scan)))
646 : {
647 : Form_pg_subscription_rel subrel;
648 : LogicalRepSequenceInfo *seq;
649 : Relation sequence_rel;
650 : MemoryContext oldctx;
651 :
652 26 : CHECK_FOR_INTERRUPTS();
653 :
654 26 : subrel = (Form_pg_subscription_rel) GETSTRUCT(tup);
655 :
656 26 : sequence_rel = try_table_open(subrel->srrelid, RowExclusiveLock);
657 :
658 : /* Skip if sequence was dropped concurrently */
659 26 : if (!sequence_rel)
660 0 : continue;
661 :
662 : /* Skip if the relation is not a sequence */
663 26 : if (sequence_rel->rd_rel->relkind != RELKIND_SEQUENCE)
664 : {
665 0 : table_close(sequence_rel, NoLock);
666 0 : continue;
667 : }
668 :
669 : /*
670 : * Worker needs to process sequences across transaction boundary, so
671 : * allocate them under long-lived context.
672 : */
673 26 : oldctx = MemoryContextSwitchTo(ApplyContext);
674 :
675 26 : seq = palloc0_object(LogicalRepSequenceInfo);
676 26 : seq->localrelid = subrel->srrelid;
677 26 : seq->nspname = get_namespace_name(RelationGetNamespace(sequence_rel));
678 26 : seq->seqname = pstrdup(RelationGetRelationName(sequence_rel));
679 26 : seqinfos = lappend(seqinfos, seq);
680 :
681 26 : MemoryContextSwitchTo(oldctx);
682 :
683 26 : table_close(sequence_rel, NoLock);
684 : }
685 :
686 : /* Cleanup */
687 18 : systable_endscan(scan);
688 18 : table_close(rel, AccessShareLock);
689 :
690 18 : CommitTransactionCommand();
691 :
692 : /*
693 : * Exit early if no catalog entries found, likely due to concurrent drops.
694 : */
695 18 : if (!seqinfos)
696 0 : return;
697 :
698 : /* Is the use of a password mandatory? */
699 36 : must_use_password = MySubscription->passwordrequired &&
700 18 : !MySubscription->ownersuperuser;
701 :
702 18 : initStringInfo(&app_name);
703 18 : appendStringInfo(&app_name, "pg_%u_sequence_sync_" UINT64_FORMAT,
704 18 : MySubscription->oid, GetSystemIdentifier());
705 :
706 : /*
707 : * Establish the connection to the publisher for sequence synchronization.
708 : */
709 18 : LogRepWorkerWalRcvConn =
710 18 : walrcv_connect(MySubscription->conninfo, true, true,
711 : must_use_password,
712 : app_name.data, &err);
713 18 : if (LogRepWorkerWalRcvConn == NULL)
714 0 : ereport(ERROR,
715 : errcode(ERRCODE_CONNECTION_FAILURE),
716 : errmsg("sequencesync worker for subscription \"%s\" could not connect to the publisher: %s",
717 : MySubscription->name, err));
718 :
719 18 : pfree(app_name.data);
720 :
721 18 : copy_sequences(LogRepWorkerWalRcvConn);
722 : }
723 :
724 : /*
725 : * Execute the initial sync with error handling. Disable the subscription,
726 : * if required.
727 : *
728 : * Note that we don't handle FATAL errors which are probably because of system
729 : * resource error and are not repeatable.
730 : */
731 : static void
732 18 : start_sequence_sync(void)
733 : {
734 : Assert(am_sequencesync_worker());
735 :
736 18 : PG_TRY();
737 : {
738 : /* Call initial sync. */
739 18 : LogicalRepSyncSequences();
740 : }
741 8 : PG_CATCH();
742 : {
743 8 : if (MySubscription->disableonerr)
744 0 : DisableSubscriptionAndExit();
745 : else
746 : {
747 : /*
748 : * Report the worker failed during sequence synchronization. Abort
749 : * the current transaction so that the stats message is sent in an
750 : * idle state.
751 : */
752 8 : AbortOutOfAnyTransaction();
753 8 : pgstat_report_subscription_error(MySubscription->oid,
754 : WORKERTYPE_SEQUENCESYNC);
755 :
756 8 : PG_RE_THROW();
757 : }
758 : }
759 10 : PG_END_TRY();
760 10 : }
761 :
762 : /* Logical Replication sequencesync worker entry point */
763 : void
764 18 : SequenceSyncWorkerMain(Datum main_arg)
765 : {
766 18 : int worker_slot = DatumGetInt32(main_arg);
767 :
768 18 : SetupApplyOrSyncWorker(worker_slot);
769 :
770 18 : start_sequence_sync();
771 :
772 10 : FinishSyncWorker();
773 : }
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