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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) 1996-2026, 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/snapmgr.h"
32 : : #include "utils/syscache.h"
33 : :
34 : : /*
35 : : * Entry of a hash table used in find_all_inheritors. See below.
36 : : */
37 : : typedef struct SeenRelsEntry
38 : : {
39 : : Oid rel_id; /* relation oid */
40 : : int list_index; /* its position in output list(s) */
41 : : } SeenRelsEntry;
42 : :
43 : : /*
44 : : * find_inheritance_children
45 : : *
46 : : * Returns a list containing the OIDs of all relations which
47 : : * inherit *directly* from the relation with OID 'parentrelId'.
48 : : *
49 : : * The specified lock type is acquired on each child relation (but not on the
50 : : * given rel; caller should already have locked it). If lockmode is NoLock
51 : : * then no locks are acquired, but caller must beware of race conditions
52 : : * against possible DROPs of child relations.
53 : : *
54 : : * Partitions marked as being detached are omitted; see
55 : : * find_inheritance_children_extended for details.
56 : : */
57 : : List *
58 : 8211 : find_inheritance_children(Oid parentrelId, LOCKMODE lockmode)
59 : : {
60 : 8211 : return find_inheritance_children_extended(parentrelId, true, lockmode,
61 : : NULL, NULL);
62 : : }
63 : :
64 : : /*
65 : : * find_inheritance_children_extended
66 : : *
67 : : * As find_inheritance_children, with more options regarding detached
68 : : * partitions.
69 : : *
70 : : * If a partition's pg_inherits row is marked "detach pending",
71 : : * *detached_exist (if not null) is set true.
72 : : *
73 : : * If omit_detached is true and there is an active snapshot (not the same as
74 : : * the catalog snapshot used to scan pg_inherits!) and a pg_inherits tuple
75 : : * marked "detach pending" is visible to that snapshot, then that partition is
76 : : * omitted from the output list. This makes partitions invisible depending on
77 : : * whether the transaction that marked those partitions as detached appears
78 : : * committed to the active snapshot. In addition, *detached_xmin (if not null)
79 : : * is set to the xmin of the row of the detached partition.
80 : : */
81 : : List *
82 : 11459 : find_inheritance_children_extended(Oid parentrelId, bool omit_detached,
83 : : LOCKMODE lockmode, bool *detached_exist,
84 : : TransactionId *detached_xmin)
85 : : {
86 : 11459 : List *list = NIL;
87 : 11459 : Relation relation;
88 : 11459 : SysScanDesc scan;
89 : 11459 : ScanKeyData key[1];
90 : 11459 : HeapTuple inheritsTuple;
91 : 11459 : Oid inhrelid;
92 : 11459 : Oid *oidarr;
93 : 11459 : int maxoids,
94 : : numoids,
95 : : i;
96 : :
97 : : /*
98 : : * Can skip the scan if pg_class shows the relation has never had a
99 : : * subclass.
100 : : */
101 [ + + ]: 11459 : if (!has_subclass(parentrelId))
102 : 6882 : return NIL;
103 : :
104 : : /*
105 : : * Scan pg_inherits and build a working array of subclass OIDs.
106 : : */
107 : 4577 : maxoids = 32;
108 : 4577 : oidarr = (Oid *) palloc(maxoids * sizeof(Oid));
109 : 4577 : numoids = 0;
110 : :
111 : 4577 : relation = table_open(InheritsRelationId, AccessShareLock);
112 : :
113 : 9154 : ScanKeyInit(&key[0],
114 : : Anum_pg_inherits_inhparent,
115 : : BTEqualStrategyNumber, F_OIDEQ,
116 : 4577 : ObjectIdGetDatum(parentrelId));
117 : :
118 : 9154 : scan = systable_beginscan(relation, InheritsParentIndexId, true,
119 : 4577 : NULL, 1, key);
120 : :
121 [ + + ]: 13407 : while ((inheritsTuple = systable_getnext(scan)) != NULL)
122 : : {
123 : : /*
124 : : * Cope with partitions concurrently being detached. When we see a
125 : : * partition marked "detach pending", we omit it from the returned set
126 : : * of visible partitions if caller requested that and the tuple's xmin
127 : : * does not appear in progress to the active snapshot. (If there's no
128 : : * active snapshot set, that means we're not running a user query, so
129 : : * it's OK to always include detached partitions in that case; if the
130 : : * xmin is still running to the active snapshot, then the partition
131 : : * has not been detached yet and so we include it.)
132 : : *
133 : : * The reason for this hack is that we want to avoid seeing the
134 : : * partition as alive in RI queries during REPEATABLE READ or
135 : : * SERIALIZABLE transactions: such queries use a different snapshot
136 : : * than the one used by regular (user) queries.
137 : : */
138 [ + - ]: 8830 : if (((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhdetachpending)
139 : : {
140 [ # # ]: 0 : if (detached_exist)
141 : 0 : *detached_exist = true;
142 : :
143 [ # # # # ]: 0 : if (omit_detached && ActiveSnapshotSet())
144 : : {
145 : 0 : TransactionId xmin;
146 : 0 : Snapshot snap;
147 : :
148 : 0 : xmin = HeapTupleHeaderGetXmin(inheritsTuple->t_data);
149 : 0 : snap = GetActiveSnapshot();
150 : :
151 [ # # ]: 0 : if (!XidInMVCCSnapshot(xmin, snap))
152 : : {
153 [ # # ]: 0 : if (detached_xmin)
154 : : {
155 : : /*
156 : : * Two detached partitions should not occur (see
157 : : * checks in MarkInheritDetached), but if they do,
158 : : * track the newer of the two. Make sure to warn the
159 : : * user, so that they can clean up. Since this is
160 : : * just a cross-check against potentially corrupt
161 : : * catalogs, we don't make it a full-fledged error
162 : : * message.
163 : : */
164 [ # # ]: 0 : if (*detached_xmin != InvalidTransactionId)
165 : : {
166 [ # # # # ]: 0 : elog(WARNING, "more than one partition pending detach found for table with OID %u",
167 : : parentrelId);
168 [ # # ]: 0 : if (TransactionIdFollows(xmin, *detached_xmin))
169 : 0 : *detached_xmin = xmin;
170 : 0 : }
171 : : else
172 : 0 : *detached_xmin = xmin;
173 : 0 : }
174 : :
175 : : /* Don't add the partition to the output list */
176 : 0 : continue;
177 : : }
178 [ # # # ]: 0 : }
179 : 0 : }
180 : :
181 : 8830 : inhrelid = ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhrelid;
182 [ + - ]: 8830 : if (numoids >= maxoids)
183 : : {
184 : 0 : maxoids *= 2;
185 : 0 : oidarr = (Oid *) repalloc(oidarr, maxoids * sizeof(Oid));
186 : 0 : }
187 : 8830 : oidarr[numoids++] = inhrelid;
188 : : }
189 : :
190 : 4577 : systable_endscan(scan);
191 : :
192 : 4577 : table_close(relation, AccessShareLock);
193 : :
194 : : /*
195 : : * If we found more than one child, sort them by OID. This ensures
196 : : * reasonably consistent behavior regardless of the vagaries of an
197 : : * indexscan. This is important since we need to be sure all backends
198 : : * lock children in the same order to avoid needless deadlocks.
199 : : */
200 [ + + ]: 4577 : if (numoids > 1)
201 : 2574 : qsort(oidarr, numoids, sizeof(Oid), oid_cmp);
202 : :
203 : : /*
204 : : * Acquire locks and build the result list.
205 : : */
206 [ + + ]: 13407 : for (i = 0; i < numoids; i++)
207 : : {
208 : 8830 : inhrelid = oidarr[i];
209 : :
210 [ + + ]: 8830 : if (lockmode != NoLock)
211 : : {
212 : : /* Get the lock to synchronize against concurrent drop */
213 : 3108 : LockRelationOid(inhrelid, lockmode);
214 : :
215 : : /*
216 : : * Now that we have the lock, double-check to see if the relation
217 : : * really exists or not. If not, assume it was dropped while we
218 : : * waited to acquire lock, and ignore it.
219 : : */
220 [ + - ]: 3108 : if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(inhrelid)))
221 : : {
222 : : /* Release useless lock */
223 : 0 : UnlockRelationOid(inhrelid, lockmode);
224 : : /* And ignore this relation */
225 : 0 : continue;
226 : : }
227 : 3108 : }
228 : :
229 : 8830 : list = lappend_oid(list, inhrelid);
230 : 8830 : }
231 : :
232 : 4577 : pfree(oidarr);
233 : :
234 : 4577 : return list;
235 : 11459 : }
236 : :
237 : :
238 : : /*
239 : : * find_all_inheritors -
240 : : * Returns a list of relation OIDs including the given rel plus
241 : : * all relations that inherit from it, directly or indirectly.
242 : : * Optionally, it also returns the number of parents found for
243 : : * each such relation within the inheritance tree rooted at the
244 : : * given rel.
245 : : *
246 : : * The specified lock type is acquired on all child relations (but not on the
247 : : * given rel; caller should already have locked it). If lockmode is NoLock
248 : : * then no locks are acquired, but caller must beware of race conditions
249 : : * against possible DROPs of child relations.
250 : : *
251 : : * NB - No current callers of this routine are interested in children being
252 : : * concurrently detached, so there's no provision to include them.
253 : : */
254 : : List *
255 : 3524 : find_all_inheritors(Oid parentrelId, LOCKMODE lockmode, List **numparents)
256 : : {
257 : : /* hash table for O(1) rel_oid -> rel_numparents cell lookup */
258 : 3524 : HTAB *seen_rels;
259 : 3524 : HASHCTL ctl;
260 : 3524 : List *rels_list,
261 : : *rel_numparents;
262 : 3524 : ListCell *l;
263 : :
264 : 3524 : ctl.keysize = sizeof(Oid);
265 : 3524 : ctl.entrysize = sizeof(SeenRelsEntry);
266 : 3524 : ctl.hcxt = CurrentMemoryContext;
267 : :
268 : 3524 : seen_rels = hash_create("find_all_inheritors temporary table",
269 : : 32, /* start small and extend */
270 : : &ctl,
271 : : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
272 : :
273 : : /*
274 : : * We build a list starting with the given rel and adding all direct and
275 : : * indirect children. We can use a single list as both the record of
276 : : * already-found rels and the agenda of rels yet to be scanned for more
277 : : * children. This is a bit tricky but works because the foreach() macro
278 : : * doesn't fetch the next list element until the bottom of the loop. Note
279 : : * that we can't keep pointers into the output lists; but an index is
280 : : * sufficient.
281 : : */
282 : 3524 : rels_list = list_make1_oid(parentrelId);
283 : 3524 : rel_numparents = list_make1_int(0);
284 : :
285 [ + - + + : 10296 : foreach(l, rels_list)
+ + ]
286 : : {
287 : 6772 : Oid currentrel = lfirst_oid(l);
288 : 6772 : List *currentchildren;
289 : 6772 : ListCell *lc;
290 : :
291 : : /* Get the direct children of this rel */
292 : 6772 : currentchildren = find_inheritance_children(currentrel, lockmode);
293 : :
294 : : /*
295 : : * Add to the queue only those children not already seen. This avoids
296 : : * making duplicate entries in case of multiple inheritance paths from
297 : : * the same parent. (It'll also keep us from getting into an infinite
298 : : * loop, though theoretically there can't be any cycles in the
299 : : * inheritance graph anyway.)
300 : : */
301 [ + + + + : 10091 : foreach(lc, currentchildren)
+ + ]
302 : : {
303 : 3319 : Oid child_oid = lfirst_oid(lc);
304 : 3319 : bool found;
305 : 3319 : SeenRelsEntry *hash_entry;
306 : :
307 : 3319 : hash_entry = hash_search(seen_rels, &child_oid, HASH_ENTER, &found);
308 [ + + ]: 3319 : if (found)
309 : : {
310 : : /* if the rel is already there, bump number-of-parents counter */
311 : 71 : ListCell *numparents_cell;
312 : :
313 : 142 : numparents_cell = list_nth_cell(rel_numparents,
314 : 71 : hash_entry->list_index);
315 : 71 : lfirst_int(numparents_cell)++;
316 : 71 : }
317 : : else
318 : : {
319 : : /* if it's not there, add it. expect 1 parent, initially. */
320 : 3248 : hash_entry->list_index = list_length(rels_list);
321 : 3248 : rels_list = lappend_oid(rels_list, child_oid);
322 : 3248 : rel_numparents = lappend_int(rel_numparents, 1);
323 : : }
324 : 3319 : }
325 : 6772 : }
326 : :
327 [ + + ]: 3524 : if (numparents)
328 : 200 : *numparents = rel_numparents;
329 : : else
330 : 3324 : list_free(rel_numparents);
331 : :
332 : 3524 : hash_destroy(seen_rels);
333 : :
334 : 7048 : return rels_list;
335 : 3524 : }
336 : :
337 : :
338 : : /*
339 : : * has_subclass - does this relation have any children?
340 : : *
341 : : * In the current implementation, has_subclass returns whether a
342 : : * particular class *might* have a subclass. It will not return the
343 : : * correct result if a class had a subclass which was later dropped.
344 : : * This is because relhassubclass in pg_class is not updated immediately
345 : : * when a subclass is dropped, primarily because of concurrency concerns.
346 : : *
347 : : * Currently has_subclass is only used as an efficiency hack to skip
348 : : * unnecessary inheritance searches, so this is OK. Note that ANALYZE
349 : : * on a childless table will clean up the obsolete relhassubclass flag.
350 : : *
351 : : * Although this doesn't actually touch pg_inherits, it seems reasonable
352 : : * to keep it here since it's normally used with the other routines here.
353 : : */
354 : : bool
355 : 11481 : has_subclass(Oid relationId)
356 : : {
357 : 11481 : HeapTuple tuple;
358 : 11481 : bool result;
359 : :
360 : 11481 : tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relationId));
361 [ + - ]: 11481 : if (!HeapTupleIsValid(tuple))
362 [ # # # # ]: 0 : elog(ERROR, "cache lookup failed for relation %u", relationId);
363 : :
364 : 11481 : result = ((Form_pg_class) GETSTRUCT(tuple))->relhassubclass;
365 : 11481 : ReleaseSysCache(tuple);
366 : 22962 : return result;
367 : 11481 : }
368 : :
369 : : /*
370 : : * has_superclass - does this relation inherit from another?
371 : : *
372 : : * Unlike has_subclass, this can be relied on to give an accurate answer.
373 : : * However, the caller must hold a lock on the given relation so that it
374 : : * can't be concurrently added to or removed from an inheritance hierarchy.
375 : : */
376 : : bool
377 : 142 : has_superclass(Oid relationId)
378 : : {
379 : 142 : Relation catalog;
380 : 142 : SysScanDesc scan;
381 : 142 : ScanKeyData skey;
382 : 142 : bool result;
383 : :
384 : 142 : catalog = table_open(InheritsRelationId, AccessShareLock);
385 : 142 : ScanKeyInit(&skey, Anum_pg_inherits_inhrelid, BTEqualStrategyNumber,
386 : 142 : F_OIDEQ, ObjectIdGetDatum(relationId));
387 : 142 : scan = systable_beginscan(catalog, InheritsRelidSeqnoIndexId, true,
388 : : NULL, 1, &skey);
389 : 142 : result = HeapTupleIsValid(systable_getnext(scan));
390 : 142 : systable_endscan(scan);
391 : 142 : table_close(catalog, AccessShareLock);
392 : :
393 : 284 : return result;
394 : 142 : }
395 : :
396 : : /*
397 : : * Given two type OIDs, determine whether the first is a complex type
398 : : * (class type) that inherits from the second.
399 : : *
400 : : * This essentially asks whether the first type is guaranteed to be coercible
401 : : * to the second. Therefore, we allow the first type to be a domain over a
402 : : * complex type that inherits from the second; that creates no difficulties.
403 : : * But the second type cannot be a domain.
404 : : */
405 : : bool
406 : 56295 : typeInheritsFrom(Oid subclassTypeId, Oid superclassTypeId)
407 : : {
408 : 56295 : bool result = false;
409 : 56295 : Oid subclassRelid;
410 : 56295 : Oid superclassRelid;
411 : 56295 : Relation inhrel;
412 : 56295 : List *visited,
413 : : *queue;
414 : 56295 : ListCell *queue_item;
415 : :
416 : : /* We need to work with the associated relation OIDs */
417 : 56295 : subclassRelid = typeOrDomainTypeRelid(subclassTypeId);
418 [ + + ]: 56295 : if (subclassRelid == InvalidOid)
419 : 54149 : return false; /* not a complex type or domain over one */
420 : 2146 : superclassRelid = typeidTypeRelid(superclassTypeId);
421 [ + + ]: 2146 : if (superclassRelid == InvalidOid)
422 : 2124 : return false; /* not a complex type */
423 : :
424 : : /* No point in searching if the superclass has no subclasses */
425 [ + + ]: 22 : if (!has_subclass(superclassRelid))
426 : 2 : return false;
427 : :
428 : : /*
429 : : * Begin the search at the relation itself, so add its relid to the queue.
430 : : */
431 : 20 : queue = list_make1_oid(subclassRelid);
432 : 20 : visited = NIL;
433 : :
434 : 20 : inhrel = table_open(InheritsRelationId, AccessShareLock);
435 : :
436 : : /*
437 : : * Use queue to do a breadth-first traversal of the inheritance graph from
438 : : * the relid supplied up to the root. Notice that we append to the queue
439 : : * inside the loop --- this is okay because the foreach() macro doesn't
440 : : * advance queue_item until the next loop iteration begins.
441 : : */
442 [ + - - + : 40 : foreach(queue_item, queue)
- + ]
443 : : {
444 : 20 : Oid this_relid = lfirst_oid(queue_item);
445 : 20 : ScanKeyData skey;
446 : 20 : SysScanDesc inhscan;
447 : 20 : HeapTuple inhtup;
448 : :
449 : : /*
450 : : * If we've seen this relid already, skip it. This avoids extra work
451 : : * in multiple-inheritance scenarios, and also protects us from an
452 : : * infinite loop in case there is a cycle in pg_inherits (though
453 : : * theoretically that shouldn't happen).
454 : : */
455 [ - + ]: 20 : if (list_member_oid(visited, this_relid))
456 : 0 : continue;
457 : :
458 : : /*
459 : : * Okay, this is a not-yet-seen relid. Add it to the list of
460 : : * already-visited OIDs, then find all the types this relid inherits
461 : : * from and add them to the queue.
462 : : */
463 : 20 : visited = lappend_oid(visited, this_relid);
464 : :
465 : 20 : ScanKeyInit(&skey,
466 : : Anum_pg_inherits_inhrelid,
467 : : BTEqualStrategyNumber, F_OIDEQ,
468 : 20 : ObjectIdGetDatum(this_relid));
469 : :
470 : 20 : inhscan = systable_beginscan(inhrel, InheritsRelidSeqnoIndexId, true,
471 : : NULL, 1, &skey);
472 : :
473 [ - + ]: 22 : while ((inhtup = systable_getnext(inhscan)) != NULL)
474 : : {
475 : 22 : Form_pg_inherits inh = (Form_pg_inherits) GETSTRUCT(inhtup);
476 : 22 : Oid inhparent = inh->inhparent;
477 : :
478 : : /* If this is the target superclass, we're done */
479 [ + + ]: 22 : if (inhparent == superclassRelid)
480 : : {
481 : 20 : result = true;
482 : 20 : break;
483 : : }
484 : :
485 : : /* Else add to queue */
486 : 2 : queue = lappend_oid(queue, inhparent);
487 [ - + + ]: 22 : }
488 : :
489 : 20 : systable_endscan(inhscan);
490 : :
491 [ + - ]: 20 : if (result)
492 : 20 : break;
493 [ - + - ]: 20 : }
494 : :
495 : : /* clean up ... */
496 : 20 : table_close(inhrel, AccessShareLock);
497 : :
498 : 20 : list_free(visited);
499 : 20 : list_free(queue);
500 : :
501 : 20 : return result;
502 : 56295 : }
503 : :
504 : : /*
505 : : * Create a single pg_inherits row with the given data
506 : : */
507 : : void
508 : 2397 : StoreSingleInheritance(Oid relationId, Oid parentOid, int32 seqNumber)
509 : : {
510 : 2397 : Datum values[Natts_pg_inherits];
511 : 2397 : bool nulls[Natts_pg_inherits];
512 : 2397 : HeapTuple tuple;
513 : 2397 : Relation inhRelation;
514 : :
515 : 2397 : inhRelation = table_open(InheritsRelationId, RowExclusiveLock);
516 : :
517 : : /*
518 : : * Make the pg_inherits entry
519 : : */
520 : 2397 : values[Anum_pg_inherits_inhrelid - 1] = ObjectIdGetDatum(relationId);
521 : 2397 : values[Anum_pg_inherits_inhparent - 1] = ObjectIdGetDatum(parentOid);
522 : 2397 : values[Anum_pg_inherits_inhseqno - 1] = Int32GetDatum(seqNumber);
523 : 2397 : values[Anum_pg_inherits_inhdetachpending - 1] = BoolGetDatum(false);
524 : :
525 : 2397 : memset(nulls, 0, sizeof(nulls));
526 : :
527 : 2397 : tuple = heap_form_tuple(RelationGetDescr(inhRelation), values, nulls);
528 : :
529 : 2397 : CatalogTupleInsert(inhRelation, tuple);
530 : :
531 : 2397 : heap_freetuple(tuple);
532 : :
533 : 2397 : table_close(inhRelation, RowExclusiveLock);
534 : 2397 : }
535 : :
536 : : /*
537 : : * DeleteInheritsTuple
538 : : *
539 : : * Delete pg_inherits tuples with the given inhrelid. inhparent may be given
540 : : * as InvalidOid, in which case all tuples matching inhrelid are deleted;
541 : : * otherwise only delete tuples with the specified inhparent.
542 : : *
543 : : * expect_detach_pending is the expected state of the inhdetachpending flag.
544 : : * If the catalog row does not match that state, an error is raised.
545 : : *
546 : : * childname is the partition name, if a table; pass NULL for regular
547 : : * inheritance or when working with other relation kinds.
548 : : *
549 : : * Returns whether at least one row was deleted.
550 : : */
551 : : bool
552 : 2929 : DeleteInheritsTuple(Oid inhrelid, Oid inhparent, bool expect_detach_pending,
553 : : const char *childname)
554 : : {
555 : 2929 : bool found = false;
556 : 2929 : Relation catalogRelation;
557 : 2929 : ScanKeyData key;
558 : 2929 : SysScanDesc scan;
559 : 2929 : HeapTuple inheritsTuple;
560 : :
561 : : /*
562 : : * Find pg_inherits entries by inhrelid.
563 : : */
564 : 2929 : catalogRelation = table_open(InheritsRelationId, RowExclusiveLock);
565 : 2929 : ScanKeyInit(&key,
566 : : Anum_pg_inherits_inhrelid,
567 : : BTEqualStrategyNumber, F_OIDEQ,
568 : 2929 : ObjectIdGetDatum(inhrelid));
569 : 2929 : scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId,
570 : : true, NULL, 1, &key);
571 : :
572 [ + + ]: 3512 : while (HeapTupleIsValid(inheritsTuple = systable_getnext(scan)))
573 : : {
574 : 583 : Oid parent;
575 : :
576 : : /* Compare inhparent if it was given, and do the actual deletion. */
577 : 583 : parent = ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhparent;
578 [ + + + + ]: 583 : if (!OidIsValid(inhparent) || parent == inhparent)
579 : : {
580 : 574 : bool detach_pending;
581 : :
582 : 574 : detach_pending =
583 : 574 : ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhdetachpending;
584 : :
585 : : /*
586 : : * Raise error depending on state. This should only happen for
587 : : * partitions, but we have no way to cross-check.
588 : : */
589 [ + + + - ]: 574 : if (detach_pending && !expect_detach_pending)
590 [ # # # # : 0 : ereport(ERROR,
# # ]
591 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
592 : : errmsg("cannot detach partition \"%s\"",
593 : : childname ? childname : "unknown relation"),
594 : : errdetail("The partition is being detached concurrently or has an unfinished detach."),
595 : : errhint("Use ALTER TABLE ... DETACH PARTITION ... FINALIZE to complete the pending detach operation.")));
596 [ + + + - ]: 574 : if (!detach_pending && expect_detach_pending)
597 [ # # # # : 0 : ereport(ERROR,
# # ]
598 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
599 : : errmsg("cannot complete detaching partition \"%s\"",
600 : : childname ? childname : "unknown relation"),
601 : : errdetail("There's no pending concurrent detach.")));
602 : :
603 : 574 : CatalogTupleDelete(catalogRelation, &inheritsTuple->t_self);
604 : 574 : found = true;
605 : 574 : }
606 : 583 : }
607 : :
608 : : /* Done */
609 : 2929 : systable_endscan(scan);
610 : 2929 : table_close(catalogRelation, RowExclusiveLock);
611 : :
612 : 5858 : return found;
613 : 2929 : }
614 : :
615 : : /*
616 : : * Return whether the pg_inherits tuple for a partition has the "detach
617 : : * pending" flag set.
618 : : */
619 : : bool
620 : 164 : PartitionHasPendingDetach(Oid partoid)
621 : : {
622 : 164 : Relation catalogRelation;
623 : 164 : ScanKeyData key;
624 : 164 : SysScanDesc scan;
625 : 164 : HeapTuple inheritsTuple;
626 : :
627 : : /* We don't have a good way to verify it is in fact a partition */
628 : :
629 : : /*
630 : : * Find the pg_inherits entry by inhrelid. (There should only be one.)
631 : : */
632 : 164 : catalogRelation = table_open(InheritsRelationId, RowExclusiveLock);
633 : 164 : ScanKeyInit(&key,
634 : : Anum_pg_inherits_inhrelid,
635 : : BTEqualStrategyNumber, F_OIDEQ,
636 : 164 : ObjectIdGetDatum(partoid));
637 : 164 : scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId,
638 : : true, NULL, 1, &key);
639 : :
640 [ + - ]: 164 : while (HeapTupleIsValid(inheritsTuple = systable_getnext(scan)))
641 : : {
642 : 164 : bool detached;
643 : :
644 : 164 : detached =
645 : 164 : ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhdetachpending;
646 : :
647 : : /* Done */
648 : 164 : systable_endscan(scan);
649 : 164 : table_close(catalogRelation, RowExclusiveLock);
650 : :
651 : 164 : return detached;
652 : 164 : }
653 : :
654 [ # # # # ]: 0 : elog(ERROR, "relation %u is not a partition", partoid);
655 : 0 : return false; /* keep compiler quiet */
656 : 164 : }
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