TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * pg_inherits.c
4 : * routines to support manipulation of the pg_inherits relation
5 : *
6 : * Note: currently, this module mostly contains inquiry functions; actual
7 : * creation and deletion of pg_inherits entries is mostly done in tablecmds.c.
8 : * Perhaps someday that code should be moved here, but it'd have to be
9 : * disentangled from other stuff such as pg_depend updates.
10 : *
11 : * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
12 : * Portions Copyright (c) 1994, Regents of the University of California
13 : *
14 : *
15 : * IDENTIFICATION
16 : * src/backend/catalog/pg_inherits.c
17 : *
18 : *-------------------------------------------------------------------------
19 : */
20 : #include "postgres.h"
21 :
22 : #include "access/genam.h"
23 : #include "access/htup_details.h"
24 : #include "access/table.h"
25 : #include "catalog/indexing.h"
26 : #include "catalog/pg_inherits.h"
27 : #include "parser/parse_type.h"
28 : #include "storage/lmgr.h"
29 : #include "utils/builtins.h"
30 : #include "utils/fmgroids.h"
31 : #include "utils/memutils.h"
32 : #include "utils/snapmgr.h"
33 : #include "utils/syscache.h"
34 :
35 : /*
36 : * Entry of a hash table used in find_all_inheritors. See below.
37 : */
38 : typedef struct SeenRelsEntry
39 : {
40 : Oid rel_id; /* relation oid */
41 : int list_index; /* its position in output list(s) */
42 : } SeenRelsEntry;
43 :
44 : /*
45 : * find_inheritance_children
46 : *
47 : * Returns a list containing the OIDs of all relations which
48 : * inherit *directly* from the relation with OID 'parentrelId'.
49 : *
50 : * The specified lock type is acquired on each child relation (but not on the
51 : * given rel; caller should already have locked it). If lockmode is NoLock
52 : * then no locks are acquired, but caller must beware of race conditions
53 : * against possible DROPs of child relations.
54 : *
55 : * Partitions marked as being detached are omitted; see
56 : * find_inheritance_children_extended for details.
57 : */
58 : List *
59 CBC 24835 : find_inheritance_children(Oid parentrelId, LOCKMODE lockmode)
60 : {
61 24835 : return find_inheritance_children_extended(parentrelId, true, lockmode,
62 : NULL, NULL);
63 : }
64 :
65 : /*
66 : * find_inheritance_children_extended
67 : *
68 : * As find_inheritance_children, with more options regarding detached
69 : * partitions.
70 : *
71 : * If a partition's pg_inherits row is marked "detach pending",
72 : * *detached_exist (if not null) is set true.
73 : *
74 : * If omit_detached is true and there is an active snapshot (not the same as
75 : * the catalog snapshot used to scan pg_inherits!) and a pg_inherits tuple
76 : * marked "detach pending" is visible to that snapshot, then that partition is
77 : * omitted from the output list. This makes partitions invisible depending on
78 : * whether the transaction that marked those partitions as detached appears
79 : * committed to the active snapshot. In addition, *detached_xmin (if not null)
80 : * is set to the xmin of the row of the detached partition.
81 : */
82 : List *
83 34663 : find_inheritance_children_extended(Oid parentrelId, bool omit_detached,
84 : LOCKMODE lockmode, bool *detached_exist,
85 : TransactionId *detached_xmin)
86 : {
87 34663 : List *list = NIL;
88 : Relation relation;
89 : SysScanDesc scan;
90 : ScanKeyData key[1];
91 : HeapTuple inheritsTuple;
92 : Oid inhrelid;
93 : Oid *oidarr;
94 : int maxoids,
95 : numoids,
96 : i;
97 :
98 : /*
99 : * Can skip the scan if pg_class shows the relation has never had a
100 : * subclass.
101 : */
102 34663 : if (!has_subclass(parentrelId))
103 21187 : return NIL;
104 :
105 : /*
106 : * Scan pg_inherits and build a working array of subclass OIDs.
107 : */
108 13476 : maxoids = 32;
109 13476 : oidarr = (Oid *) palloc(maxoids * sizeof(Oid));
110 13476 : numoids = 0;
111 :
112 13476 : relation = table_open(InheritsRelationId, AccessShareLock);
113 :
114 13476 : ScanKeyInit(&key[0],
115 : Anum_pg_inherits_inhparent,
116 : BTEqualStrategyNumber, F_OIDEQ,
117 : ObjectIdGetDatum(parentrelId));
118 :
119 13476 : scan = systable_beginscan(relation, InheritsParentIndexId, true,
120 : NULL, 1, key);
121 :
122 39489 : while ((inheritsTuple = systable_getnext(scan)) != NULL)
123 : {
124 : /*
125 : * Cope with partitions concurrently being detached. When we see a
126 : * partition marked "detach pending", we omit it from the returned set
127 : * of visible partitions if caller requested that and the tuple's xmin
128 : * does not appear in progress to the active snapshot. (If there's no
129 : * active snapshot set, that means we're not running a user query, so
130 : * it's OK to always include detached partitions in that case; if the
131 : * xmin is still running to the active snapshot, then the partition
132 : * has not been detached yet and so we include it.)
133 : *
134 : * The reason for this hack is that we want to avoid seeing the
135 : * partition as alive in RI queries during REPEATABLE READ or
136 : * SERIALIZABLE transactions: such queries use a different snapshot
137 : * than the one used by regular (user) queries.
138 : */
139 26013 : if (((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhdetachpending)
140 : {
141 58 : if (detached_exist)
142 56 : *detached_exist = true;
143 :
144 58 : if (omit_detached && ActiveSnapshotSet())
145 : {
146 : TransactionId xmin;
147 : Snapshot snap;
148 :
149 47 : xmin = HeapTupleHeaderGetXmin(inheritsTuple->t_data);
150 47 : snap = GetActiveSnapshot();
151 :
152 47 : if (!XidInMVCCSnapshot(xmin, snap))
153 : {
154 35 : if (detached_xmin)
155 : {
156 : /*
157 : * Two detached partitions should not occur (see
158 : * checks in MarkInheritDetached), but if they do,
159 : * track the newer of the two. Make sure to warn the
160 : * user, so that they can clean up. Since this is
161 : * just a cross-check against potentially corrupt
162 : * catalogs, we don't make it a full-fledged error
163 : * message.
164 : */
165 33 : if (*detached_xmin != InvalidTransactionId)
166 : {
167 UBC 0 : elog(WARNING, "more than one partition pending detach found for table with OID %u",
168 : parentrelId);
169 0 : if (TransactionIdFollows(xmin, *detached_xmin))
170 0 : *detached_xmin = xmin;
171 : }
172 : else
173 CBC 33 : *detached_xmin = xmin;
174 : }
175 :
176 : /* Don't add the partition to the output list */
177 35 : continue;
178 : }
179 : }
180 : }
181 :
182 25978 : inhrelid = ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhrelid;
183 25978 : if (numoids >= maxoids)
184 : {
185 UBC 0 : maxoids *= 2;
186 0 : oidarr = (Oid *) repalloc(oidarr, maxoids * sizeof(Oid));
187 : }
188 CBC 25978 : oidarr[numoids++] = inhrelid;
189 : }
190 :
191 13476 : systable_endscan(scan);
192 :
193 13476 : table_close(relation, AccessShareLock);
194 :
195 : /*
196 : * If we found more than one child, sort them by OID. This ensures
197 : * reasonably consistent behavior regardless of the vagaries of an
198 : * indexscan. This is important since we need to be sure all backends
199 : * lock children in the same order to avoid needless deadlocks.
200 : */
201 13476 : if (numoids > 1)
202 7733 : qsort(oidarr, numoids, sizeof(Oid), oid_cmp);
203 :
204 : /*
205 : * Acquire locks and build the result list.
206 : */
207 39454 : for (i = 0; i < numoids; i++)
208 : {
209 25978 : inhrelid = oidarr[i];
210 :
211 25978 : if (lockmode != NoLock)
212 : {
213 : /* Get the lock to synchronize against concurrent drop */
214 7433 : LockRelationOid(inhrelid, lockmode);
215 :
216 : /*
217 : * Now that we have the lock, double-check to see if the relation
218 : * really exists or not. If not, assume it was dropped while we
219 : * waited to acquire lock, and ignore it.
220 : */
221 7433 : if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(inhrelid)))
222 : {
223 : /* Release useless lock */
224 1 : UnlockRelationOid(inhrelid, lockmode);
225 : /* And ignore this relation */
226 1 : continue;
227 : }
228 : }
229 :
230 25977 : list = lappend_oid(list, inhrelid);
231 : }
232 :
233 13476 : pfree(oidarr);
234 :
235 13476 : return list;
236 : }
237 :
238 :
239 : /*
240 : * find_all_inheritors -
241 : * Returns a list of relation OIDs including the given rel plus
242 : * all relations that inherit from it, directly or indirectly.
243 : * Optionally, it also returns the number of parents found for
244 : * each such relation within the inheritance tree rooted at the
245 : * given rel.
246 : *
247 : * The specified lock type is acquired on all child relations (but not on the
248 : * given rel; caller should already have locked it). If lockmode is NoLock
249 : * then no locks are acquired, but caller must beware of race conditions
250 : * against possible DROPs of child relations.
251 : *
252 : * NB - No current callers of this routine are interested in children being
253 : * concurrently detached, so there's no provision to include them.
254 : */
255 : List *
256 11041 : find_all_inheritors(Oid parentrelId, LOCKMODE lockmode, List **numparents)
257 : {
258 : /* hash table for O(1) rel_oid -> rel_numparents cell lookup */
259 : HTAB *seen_rels;
260 : HASHCTL ctl;
261 : List *rels_list,
262 : *rel_numparents;
263 : ListCell *l;
264 :
265 11041 : ctl.keysize = sizeof(Oid);
266 11041 : ctl.entrysize = sizeof(SeenRelsEntry);
267 11041 : ctl.hcxt = CurrentMemoryContext;
268 :
269 11041 : seen_rels = hash_create("find_all_inheritors temporary table",
270 : 32, /* start small and extend */
271 : &ctl,
272 : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
273 :
274 : /*
275 : * We build a list starting with the given rel and adding all direct and
276 : * indirect children. We can use a single list as both the record of
277 : * already-found rels and the agenda of rels yet to be scanned for more
278 : * children. This is a bit tricky but works because the foreach() macro
279 : * doesn't fetch the next list element until the bottom of the loop. Note
280 : * that we can't keep pointers into the output lists; but an index is
281 : * sufficient.
282 : */
283 11041 : rels_list = list_make1_oid(parentrelId);
284 11041 : rel_numparents = list_make1_int(0);
285 :
286 32181 : foreach(l, rels_list)
287 : {
288 21140 : Oid currentrel = lfirst_oid(l);
289 : List *currentchildren;
290 : ListCell *lc;
291 :
292 : /* Get the direct children of this rel */
293 21140 : currentchildren = find_inheritance_children(currentrel, lockmode);
294 :
295 : /*
296 : * Add to the queue only those children not already seen. This avoids
297 : * making duplicate entries in case of multiple inheritance paths from
298 : * the same parent. (It'll also keep us from getting into an infinite
299 : * loop, though theoretically there can't be any cycles in the
300 : * inheritance graph anyway.)
301 : */
302 31457 : foreach(lc, currentchildren)
303 : {
304 10317 : Oid child_oid = lfirst_oid(lc);
305 : bool found;
306 : SeenRelsEntry *hash_entry;
307 :
308 10317 : hash_entry = hash_search(seen_rels, &child_oid, HASH_ENTER, &found);
309 10317 : if (found)
310 : {
311 : /* if the rel is already there, bump number-of-parents counter */
312 : ListCell *numparents_cell;
313 :
314 218 : numparents_cell = list_nth_cell(rel_numparents,
315 : hash_entry->list_index);
316 218 : lfirst_int(numparents_cell)++;
317 : }
318 : else
319 : {
320 : /* if it's not there, add it. expect 1 parent, initially. */
321 10099 : hash_entry->list_index = list_length(rels_list);
322 10099 : rels_list = lappend_oid(rels_list, child_oid);
323 10099 : rel_numparents = lappend_int(rel_numparents, 1);
324 : }
325 : }
326 : }
327 :
328 11041 : if (numparents)
329 503 : *numparents = rel_numparents;
330 : else
331 10538 : list_free(rel_numparents);
332 :
333 11041 : hash_destroy(seen_rels);
334 :
335 11041 : return rels_list;
336 : }
337 :
338 :
339 : /*
340 : * has_subclass - does this relation have any children?
341 : *
342 : * In the current implementation, has_subclass returns whether a
343 : * particular class *might* have a subclass. It will not return the
344 : * correct result if a class had a subclass which was later dropped.
345 : * This is because relhassubclass in pg_class is not updated immediately
346 : * when a subclass is dropped, primarily because of concurrency concerns.
347 : *
348 : * Currently has_subclass is only used as an efficiency hack to skip
349 : * unnecessary inheritance searches, so this is OK. Note that ANALYZE
350 : * on a childless table will clean up the obsolete relhassubclass flag.
351 : *
352 : * Although this doesn't actually touch pg_inherits, it seems reasonable
353 : * to keep it here since it's normally used with the other routines here.
354 : */
355 : bool
356 185186 : has_subclass(Oid relationId)
357 : {
358 : HeapTuple tuple;
359 : bool result;
360 :
361 185186 : tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relationId));
362 185186 : if (!HeapTupleIsValid(tuple))
363 UBC 0 : elog(ERROR, "cache lookup failed for relation %u", relationId);
364 :
365 CBC 185186 : result = ((Form_pg_class) GETSTRUCT(tuple))->relhassubclass;
366 185186 : ReleaseSysCache(tuple);
367 185186 : return result;
368 : }
369 :
370 : /*
371 : * has_superclass - does this relation inherit from another?
372 : *
373 : * Unlike has_subclass, this can be relied on to give an accurate answer.
374 : * However, the caller must hold a lock on the given relation so that it
375 : * can't be concurrently added to or removed from an inheritance hierarchy.
376 : */
377 : bool
378 274 : has_superclass(Oid relationId)
379 : {
380 : Relation catalog;
381 : SysScanDesc scan;
382 : ScanKeyData skey;
383 : bool result;
384 :
385 274 : catalog = table_open(InheritsRelationId, AccessShareLock);
386 274 : ScanKeyInit(&skey, Anum_pg_inherits_inhrelid, BTEqualStrategyNumber,
387 : F_OIDEQ, ObjectIdGetDatum(relationId));
388 274 : scan = systable_beginscan(catalog, InheritsRelidSeqnoIndexId, true,
389 : NULL, 1, &skey);
390 274 : result = HeapTupleIsValid(systable_getnext(scan));
391 274 : systable_endscan(scan);
392 274 : table_close(catalog, AccessShareLock);
393 :
394 274 : return result;
395 : }
396 :
397 : /*
398 : * Given two type OIDs, determine whether the first is a complex type
399 : * (class type) that inherits from the second.
400 : *
401 : * This essentially asks whether the first type is guaranteed to be coercible
402 : * to the second. Therefore, we allow the first type to be a domain over a
403 : * complex type that inherits from the second; that creates no difficulties.
404 : * But the second type cannot be a domain.
405 : */
406 : bool
407 618498 : typeInheritsFrom(Oid subclassTypeId, Oid superclassTypeId)
408 : {
409 618498 : bool result = false;
410 : Oid subclassRelid;
411 : Oid superclassRelid;
412 : Relation inhrel;
413 : List *visited,
414 : *queue;
415 : ListCell *queue_item;
416 :
417 : /* We need to work with the associated relation OIDs */
418 618498 : subclassRelid = typeOrDomainTypeRelid(subclassTypeId);
419 618498 : if (subclassRelid == InvalidOid)
420 612383 : return false; /* not a complex type or domain over one */
421 6115 : superclassRelid = typeidTypeRelid(superclassTypeId);
422 6115 : if (superclassRelid == InvalidOid)
423 6055 : return false; /* not a complex type */
424 :
425 : /* No point in searching if the superclass has no subclasses */
426 60 : if (!has_subclass(superclassRelid))
427 6 : return false;
428 :
429 : /*
430 : * Begin the search at the relation itself, so add its relid to the queue.
431 : */
432 54 : queue = list_make1_oid(subclassRelid);
433 54 : visited = NIL;
434 :
435 54 : inhrel = table_open(InheritsRelationId, AccessShareLock);
436 :
437 : /*
438 : * Use queue to do a breadth-first traversal of the inheritance graph from
439 : * the relid supplied up to the root. Notice that we append to the queue
440 : * inside the loop --- this is okay because the foreach() macro doesn't
441 : * advance queue_item until the next loop iteration begins.
442 : */
443 54 : foreach(queue_item, queue)
444 : {
445 54 : Oid this_relid = lfirst_oid(queue_item);
446 : ScanKeyData skey;
447 : SysScanDesc inhscan;
448 : HeapTuple inhtup;
449 :
450 : /*
451 : * If we've seen this relid already, skip it. This avoids extra work
452 : * in multiple-inheritance scenarios, and also protects us from an
453 : * infinite loop in case there is a cycle in pg_inherits (though
454 : * theoretically that shouldn't happen).
455 : */
456 54 : if (list_member_oid(visited, this_relid))
457 UBC 0 : continue;
458 :
459 : /*
460 : * Okay, this is a not-yet-seen relid. Add it to the list of
461 : * already-visited OIDs, then find all the types this relid inherits
462 : * from and add them to the queue.
463 : */
464 CBC 54 : visited = lappend_oid(visited, this_relid);
465 :
466 54 : ScanKeyInit(&skey,
467 : Anum_pg_inherits_inhrelid,
468 : BTEqualStrategyNumber, F_OIDEQ,
469 : ObjectIdGetDatum(this_relid));
470 :
471 54 : inhscan = systable_beginscan(inhrel, InheritsRelidSeqnoIndexId, true,
472 : NULL, 1, &skey);
473 :
474 60 : while ((inhtup = systable_getnext(inhscan)) != NULL)
475 : {
476 60 : Form_pg_inherits inh = (Form_pg_inherits) GETSTRUCT(inhtup);
477 60 : Oid inhparent = inh->inhparent;
478 :
479 : /* If this is the target superclass, we're done */
480 60 : if (inhparent == superclassRelid)
481 : {
482 54 : result = true;
483 54 : break;
484 : }
485 :
486 : /* Else add to queue */
487 6 : queue = lappend_oid(queue, inhparent);
488 : }
489 :
490 54 : systable_endscan(inhscan);
491 :
492 54 : if (result)
493 54 : break;
494 : }
495 :
496 : /* clean up ... */
497 54 : table_close(inhrel, AccessShareLock);
498 :
499 54 : list_free(visited);
500 54 : list_free(queue);
501 :
502 54 : return result;
503 : }
504 :
505 : /*
506 : * Create a single pg_inherits row with the given data
507 : */
508 : void
509 6577 : StoreSingleInheritance(Oid relationId, Oid parentOid, int32 seqNumber)
510 : {
511 : Datum values[Natts_pg_inherits];
512 : bool nulls[Natts_pg_inherits];
513 : HeapTuple tuple;
514 : Relation inhRelation;
515 :
516 6577 : inhRelation = table_open(InheritsRelationId, RowExclusiveLock);
517 :
518 : /*
519 : * Make the pg_inherits entry
520 : */
521 6577 : values[Anum_pg_inherits_inhrelid - 1] = ObjectIdGetDatum(relationId);
522 6577 : values[Anum_pg_inherits_inhparent - 1] = ObjectIdGetDatum(parentOid);
523 6577 : values[Anum_pg_inherits_inhseqno - 1] = Int32GetDatum(seqNumber);
524 6577 : values[Anum_pg_inherits_inhdetachpending - 1] = BoolGetDatum(false);
525 :
526 6577 : memset(nulls, 0, sizeof(nulls));
527 :
528 6577 : tuple = heap_form_tuple(RelationGetDescr(inhRelation), values, nulls);
529 :
530 6577 : CatalogTupleInsert(inhRelation, tuple);
531 :
532 6577 : heap_freetuple(tuple);
533 :
534 6577 : table_close(inhRelation, RowExclusiveLock);
535 6577 : }
536 :
537 : /*
538 : * DeleteInheritsTuple
539 : *
540 : * Delete pg_inherits tuples with the given inhrelid. inhparent may be given
541 : * as InvalidOid, in which case all tuples matching inhrelid are deleted;
542 : * otherwise only delete tuples with the specified inhparent.
543 : *
544 : * expect_detach_pending is the expected state of the inhdetachpending flag.
545 : * If the catalog row does not match that state, an error is raised.
546 : *
547 : * childname is the partition name, if a table; pass NULL for regular
548 : * inheritance or when working with other relation kinds.
549 : *
550 : * Returns whether at least one row was deleted.
551 : */
552 : bool
553 10556 : DeleteInheritsTuple(Oid inhrelid, Oid inhparent, bool expect_detach_pending,
554 : const char *childname)
555 : {
556 10556 : bool found = false;
557 : Relation catalogRelation;
558 : ScanKeyData key;
559 : SysScanDesc scan;
560 : HeapTuple inheritsTuple;
561 :
562 : /*
563 : * Find pg_inherits entries by inhrelid.
564 : */
565 10556 : catalogRelation = table_open(InheritsRelationId, RowExclusiveLock);
566 10556 : ScanKeyInit(&key,
567 : Anum_pg_inherits_inhrelid,
568 : BTEqualStrategyNumber, F_OIDEQ,
569 : ObjectIdGetDatum(inhrelid));
570 10556 : scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId,
571 : true, NULL, 1, &key);
572 :
573 11806 : while (HeapTupleIsValid(inheritsTuple = systable_getnext(scan)))
574 : {
575 : Oid parent;
576 :
577 : /* Compare inhparent if it was given, and do the actual deletion. */
578 1250 : parent = ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhparent;
579 1250 : if (!OidIsValid(inhparent) || parent == inhparent)
580 : {
581 : bool detach_pending;
582 :
583 1238 : detach_pending =
584 1238 : ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhdetachpending;
585 :
586 : /*
587 : * Raise error depending on state. This should only happen for
588 : * partitions, but we have no way to cross-check.
589 : */
590 1238 : if (detach_pending && !expect_detach_pending)
591 UBC 0 : ereport(ERROR,
592 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
593 : errmsg("cannot detach partition \"%s\"",
594 : childname ? childname : "unknown relation"),
595 : errdetail("The partition is being detached concurrently or has an unfinished detach."),
596 : errhint("Use ALTER TABLE ... DETACH PARTITION ... FINALIZE to complete the pending detach operation.")));
597 CBC 1238 : if (!detach_pending && expect_detach_pending)
598 UBC 0 : ereport(ERROR,
599 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
600 : errmsg("cannot complete detaching partition \"%s\"",
601 : childname ? childname : "unknown relation"),
602 : errdetail("There's no pending concurrent detach.")));
603 :
604 CBC 1238 : CatalogTupleDelete(catalogRelation, &inheritsTuple->t_self);
605 1238 : found = true;
606 : }
607 : }
608 :
609 : /* Done */
610 10556 : systable_endscan(scan);
611 10556 : table_close(catalogRelation, RowExclusiveLock);
612 :
613 10556 : return found;
614 : }
615 :
616 : /*
617 : * Return whether the pg_inherits tuple for a partition has the "detach
618 : * pending" flag set.
619 : */
620 : bool
621 562 : PartitionHasPendingDetach(Oid partoid)
622 : {
623 : Relation catalogRelation;
624 : ScanKeyData key;
625 : SysScanDesc scan;
626 : HeapTuple inheritsTuple;
627 :
628 : /* We don't have a good way to verify it is in fact a partition */
629 :
630 : /*
631 : * Find the pg_inherits entry by inhrelid. (There should only be one.)
632 : */
633 562 : catalogRelation = table_open(InheritsRelationId, RowExclusiveLock);
634 562 : ScanKeyInit(&key,
635 : Anum_pg_inherits_inhrelid,
636 : BTEqualStrategyNumber, F_OIDEQ,
637 : ObjectIdGetDatum(partoid));
638 562 : scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId,
639 : true, NULL, 1, &key);
640 :
641 562 : while (HeapTupleIsValid(inheritsTuple = systable_getnext(scan)))
642 : {
643 : bool detached;
644 :
645 562 : detached =
646 562 : ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhdetachpending;
647 :
648 : /* Done */
649 562 : systable_endscan(scan);
650 562 : table_close(catalogRelation, RowExclusiveLock);
651 :
652 562 : return detached;
653 : }
654 :
655 UBC 0 : elog(ERROR, "relation %u is not a partition", partoid);
656 : return false; /* keep compiler quiet */
657 : }
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