| blob | 2afc550540c227da164e099b3ef280fc6a2e74d0 |
1 /*-------------------------------------------------------------------------
2 *
3 * dependency.c
4 * Routines to support inter-object dependencies.
5 *
6 *
7 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
9 *
10 * IDENTIFICATION
11 * src/backend/catalog/dependency.c
12 *
13 *-------------------------------------------------------------------------
14 */
89 /*
90 * Deletion processing requires additional state for each ObjectAddress that
91 * it's planning to delete. For simplicity and code-sharing we make the
92 * ObjectAddresses code support arrays with or without this extra state.
93 */
95 {
100 /* ObjectAddressExtra flag bits */
112 /* expansible list of ObjectAddresses */
113 struct ObjectAddresses
114 {
119 };
121 /* typedef ObjectAddresses appears in dependency.h */
123 /* threaded list of ObjectAddresses, for recursion detection */
125 {
131 /* temporary storage in findDependentObjects */
133 {
138 /* for find_expr_references_walker */
140 {
154 DropBehavior behavior,
180 /*
181 * Go through the objects given running the final actions on them, and execute
182 * the actual deletion.
183 */
184 static void
187 {
190 /*
191 * Keep track of objects for event triggers, if necessary.
192 */
194 {
196 {
210 {
212 }
213 }
214 }
216 /*
217 * Delete all the objects in the proper order, except that if told to, we
218 * should skip the original object(s).
219 */
221 {
230 }
231 }
233 /*
234 * performDeletion: attempt to drop the specified object. If CASCADE
235 * behavior is specified, also drop any dependent objects (recursively).
236 * If RESTRICT behavior is specified, error out if there are any dependent
237 * objects, except for those that should be implicitly dropped anyway
238 * according to the dependency type.
239 *
240 * This is the outer control routine for all forms of DROP that drop objects
241 * that can participate in dependencies. Note that performMultipleDeletions
242 * is a variant on the same theme; if you change anything here you'll likely
243 * need to fix that too.
244 *
245 * Bits in the flags argument can include:
246 *
247 * PERFORM_DELETION_INTERNAL: indicates that the drop operation is not the
248 * direct result of a user-initiated action. For example, when a temporary
249 * schema is cleaned out so that a new backend can use it, or when a column
250 * default is dropped as an intermediate step while adding a new one, that's
251 * an internal operation. On the other hand, when we drop something because
252 * the user issued a DROP statement against it, that's not internal. Currently
253 * this suppresses calling event triggers and making some permissions checks.
254 *
255 * PERFORM_DELETION_CONCURRENTLY: perform the drop concurrently. This does
256 * not currently work for anything except dropping indexes; don't set it for
257 * other object types or you may get strange results.
258 *
259 * PERFORM_DELETION_QUIETLY: reduce message level from NOTICE to DEBUG2.
260 *
261 * PERFORM_DELETION_SKIP_ORIGINAL: do not delete the specified object(s),
262 * but only what depends on it/them.
263 *
264 * PERFORM_DELETION_SKIP_EXTENSIONS: do not delete extensions, even when
265 * deleting objects that are part of an extension. This should generally
266 * be used only when dropping temporary objects.
267 *
268 * PERFORM_DELETION_CONCURRENT_LOCK: perform the drop normally but with a lock
269 * as if it were concurrent. This is used by REINDEX CONCURRENTLY.
270 *
271 */
272 void
275 {
276 Relation depRel;
279 /*
280 * We save some cycles by opening pg_depend just once and passing the
281 * Relation pointer down to all the recursive deletion steps.
282 */
285 /*
286 * Acquire deletion lock on the target object. (Ideally the caller has
287 * done this already, but many places are sloppy about it.)
288 */
291 /*
292 * Construct a list of objects to delete (ie, the given object plus
293 * everything directly or indirectly dependent on it).
294 */
298 DEPFLAG_ORIGINAL,
299 flags,
301 targetObjects,
305 /*
306 * Check if deletion is allowed, and report about cascaded deletes.
307 */
309 behavior,
310 flags,
311 object);
313 /* do the deed */
316 /* And clean up */
320 }
322 /*
323 * performMultipleDeletions: Similar to performDeletion, but act on multiple
324 * objects at once.
325 *
326 * The main difference from issuing multiple performDeletion calls is that the
327 * list of objects that would be implicitly dropped, for each object to be
328 * dropped, is the union of the implicit-object list for all objects. This
329 * makes each check be more relaxed.
330 */
331 void
334 {
335 Relation depRel;
339 /* No work if no objects... */
343 /*
344 * We save some cycles by opening pg_depend just once and passing the
345 * Relation pointer down to all the recursive deletion steps.
346 */
349 /*
350 * Construct a list of objects to delete (ie, the given objects plus
351 * everything directly or indirectly dependent on them). Note that
352 * because we pass the whole objects list as pendingObjects context, we
353 * won't get a failure from trying to delete an object that is internally
354 * dependent on another one in the list; we'll just skip that object and
355 * delete it when we reach its owner.
356 */
360 {
363 /*
364 * Acquire deletion lock on each target object. (Ideally the caller
365 * has done this already, but many places are sloppy about it.)
366 */
370 DEPFLAG_ORIGINAL,
371 flags,
373 targetObjects,
374 objects,
376 }
378 /*
379 * Check if deletion is allowed, and report about cascaded deletes.
380 *
381 * If there's exactly one object being deleted, report it the same way as
382 * in performDeletion(), else we have to be vaguer.
383 */
385 behavior,
386 flags,
389 /* do the deed */
392 /* And clean up */
396 }
398 /*
399 * findDependentObjects - find all objects that depend on 'object'
400 *
401 * For every object that depends on the starting object, acquire a deletion
402 * lock on the object, add it to targetObjects (if not already there),
403 * and recursively find objects that depend on it. An object's dependencies
404 * will be placed into targetObjects before the object itself; this means
405 * that the finished list's order represents a safe deletion order.
406 *
407 * The caller must already have a deletion lock on 'object' itself,
408 * but must not have added it to targetObjects. (Note: there are corner
409 * cases where we won't add the object either, and will also release the
410 * caller-taken lock. This is a bit ugly, but the API is set up this way
411 * to allow easy rechecking of an object's liveness after we lock it. See
412 * notes within the function.)
413 *
414 * When dropping a whole object (subId = 0), we find dependencies for
415 * its sub-objects too.
416 *
417 * object: the object to add to targetObjects and find dependencies on
418 * objflags: flags to be ORed into the object's targetObjects entry
419 * flags: PERFORM_DELETION_xxx flags for the deletion operation as a whole
420 * stack: list of objects being visited in current recursion; topmost item
421 * is the object that we recursed from (NULL for external callers)
422 * targetObjects: list of objects that are scheduled to be deleted
423 * pendingObjects: list of other objects slated for destruction, but
424 * not necessarily in targetObjects yet (can be NULL if none)
425 * *depRel: already opened pg_depend relation
426 *
427 * Note: objflags describes the reason for visiting this particular object
428 * at this time, and is not passed down when recursing. The flags argument
429 * is passed down, since it describes what we're doing overall.
430 */
431 static void
439 {
442 SysScanDesc scan;
443 HeapTuple tup;
444 ObjectAddress otherObject;
445 ObjectAddress owningObject;
446 ObjectAddress partitionObject;
450 ObjectAddressStack mystack;
451 ObjectAddressExtra extra;
453 /*
454 * If the target object is already being visited in an outer recursion
455 * level, just report the current objflags back to that level and exit.
456 * This is needed to avoid infinite recursion in the face of circular
457 * dependencies.
458 *
459 * The stack check alone would result in dependency loops being broken at
460 * an arbitrary point, ie, the first member object of the loop to be
461 * visited is the last one to be deleted. This is obviously unworkable.
462 * However, the check for internal dependency below guarantees that we
463 * will not break a loop at an internal dependency: if we enter the loop
464 * at an "owned" object we will switch and start at the "owning" object
465 * instead. We could probably hack something up to avoid breaking at an
466 * auto dependency, too, if we had to. However there are no known cases
467 * where that would be necessary.
468 */
472 /*
473 * since this function recurses, it could be driven to stack overflow,
474 * because of the deep dependency tree, not only due to dependency loops.
475 */
478 /*
479 * It's also possible that the target object has already been completely
480 * processed and put into targetObjects. If so, again we just add the
481 * specified objflags to its entry and return.
482 *
483 * (Note: in these early-exit cases we could release the caller-taken
484 * lock, since the object is presumably now locked multiple times; but it
485 * seems not worth the cycles.)
486 */
490 /*
491 * If the target object is pinned, we can just error out immediately; it
492 * won't have any objects recorded as depending on it.
493 */
500 /*
501 * The target object might be internally dependent on some other object
502 * (its "owner"), and/or be a member of an extension (also considered its
503 * owner). If so, and if we aren't recursing from the owning object, we
504 * have to transform this deletion request into a deletion request of the
505 * owning object. (We'll eventually recurse back to this object, but the
506 * owning object has to be visited first so it will be deleted after.) The
507 * way to find out about this is to scan the pg_depend entries that show
508 * what this object depends on.
509 */
511 Anum_pg_depend_classid,
515 Anum_pg_depend_objid,
519 {
520 /* Consider only dependencies of this sub-object */
522 Anum_pg_depend_objsubid,
526 }
527 else
528 {
529 /* Consider dependencies of this object and any sub-objects it has */
531 }
536 /* initialize variables that loop may fill */
541 {
548 /*
549 * When scanning dependencies of a whole object, we may find rows
550 * linking sub-objects of the object to the object itself. (Normally,
551 * such a dependency is implicit, but we must make explicit ones in
552 * some cases involving partitioning.) We must ignore such rows to
553 * avoid infinite recursion.
554 */
561 {
565 /* no problem */
570 /*
571 * If told to, ignore EXTENSION dependencies altogether. This
572 * flag is normally used to prevent dropping extensions during
573 * temporary-object cleanup, even if a temp object was created
574 * during an extension script.
575 */
579 /*
580 * If the other object is the extension currently being
581 * created/altered, ignore this dependency and continue with
582 * the deletion. This allows dropping of an extension's
583 * objects within the extension's scripts, as well as corner
584 * cases such as dropping a transient object created within
585 * such a script.
586 */
592 /* Otherwise, treat this like an internal dependency */
593 /* FALL THRU */
597 /*
598 * This object is part of the internal implementation of
599 * another object, or is part of the extension that is the
600 * other object. We have three cases:
601 *
602 * 1. At the outermost recursion level, we must disallow the
603 * DROP. However, if the owning object is listed in
604 * pendingObjects, just release the caller's lock and return;
605 * we'll eventually complete the DROP when we reach that entry
606 * in the pending list.
607 *
608 * Note: the above statement is true only if this pg_depend
609 * entry still exists by then; in principle, therefore, we
610 * could miss deleting an item the user told us to delete.
611 * However, no inconsistency can result: since we're at outer
612 * level, there is no object depending on this one.
613 */
615 {
618 {
620 /* need to release caller's lock; see notes below */
623 }
625 /*
626 * We postpone actually issuing the error message until
627 * after this loop, so that we can make the behavior
628 * independent of the ordering of pg_depend entries, at
629 * least if there's not more than one INTERNAL and one
630 * EXTENSION dependency. (If there's more, we'll complain
631 * about a random one of them.) Prefer to complain about
632 * EXTENSION, since that's generally a more important
633 * dependency.
634 */
639 }
641 /*
642 * 2. When recursing from the other end of this dependency,
643 * it's okay to continue with the deletion. This holds when
644 * recursing from a whole object that includes the nominal
645 * other end as a component, too. Since there can be more
646 * than one "owning" object, we have to allow matches that are
647 * more than one level down in the stack.
648 */
652 /*
653 * 3. Not all the owning objects have been visited, so
654 * transform this deletion request into a delete of this
655 * owning object.
656 *
657 * First, release caller's lock on this object and get
658 * deletion lock on the owning object. (We must release
659 * caller's lock to avoid deadlock against a concurrent
660 * deletion of the owning object.)
661 */
665 /*
666 * The owning object might have been deleted while we waited
667 * to lock it; if so, neither it nor the current object are
668 * interesting anymore. We test this by checking the
669 * pg_depend entry (see notes below).
670 */
672 {
676 }
678 /*
679 * One way or the other, we're done with the scan; might as
680 * well close it down before recursing, to reduce peak
681 * resource consumption.
682 */
685 /*
686 * Okay, recurse to the owning object instead of proceeding.
687 *
688 * We do not need to stack the current object; we want the
689 * traversal order to be as if the original reference had
690 * linked to the owning object instead of this one.
691 *
692 * The dependency type is a "reverse" dependency: we need to
693 * delete the owning object if this one is to be deleted, but
694 * this linkage is never a reason for an automatic deletion.
695 */
697 DEPFLAG_REVERSE,
698 flags,
699 stack,
700 targetObjects,
701 pendingObjects,
702 depRel);
704 /*
705 * The current target object should have been added to
706 * targetObjects while processing the owning object; but it
707 * probably got only the flag bits associated with the
708 * dependency we're looking at. We need to add the objflags
709 * that were passed to this recursion level, too, else we may
710 * get a bogus failure in reportDependentObjects (if, for
711 * example, we were called due to a partition dependency).
712 *
713 * If somehow the current object didn't get scheduled for
714 * deletion, bleat. (That would imply that somebody deleted
715 * this dependency record before the recursion got to it.)
716 * Another idea would be to reacquire lock on the current
717 * object and resume trying to delete it, but it seems not
718 * worth dealing with the race conditions inherent in that.
719 */
721 targetObjects))
726 /* And we're done here. */
731 /*
732 * Remember that this object has a partition-type dependency.
733 * After the dependency scan, we'll complain if we didn't find
734 * a reason to delete one of its partition dependencies.
735 */
738 /*
739 * Also remember the primary partition owner, for error
740 * messages. If there are multiple primary owners (which
741 * there should not be), we'll report a random one of them.
742 */
748 /*
749 * Only use secondary partition owners in error messages if we
750 * find no primary owner (which probably shouldn't happen).
751 */
755 /*
756 * Remember that this object has a partition-type dependency.
757 * After the dependency scan, we'll complain if we didn't find
758 * a reason to delete one of its partition dependencies.
759 */
767 }
768 }
772 /*
773 * If we found an INTERNAL or EXTENSION dependency when we're at outer
774 * level, complain about it now. If we also found a PARTITION dependency,
775 * we prefer to report the PARTITION dependency. This is arbitrary but
776 * seems to be more useful in practice.
777 */
779 {
784 else
792 }
794 /*
795 * Next, identify all objects that directly depend on the current object.
796 * To ensure predictable deletion order, we collect them up in
797 * dependentObjects and sort the list before actually recursing. (The
798 * deletion order would be valid in any case, but doing this ensures
799 * consistent output from DROP CASCADE commands, which is helpful for
800 * regression testing.)
801 */
808 Anum_pg_depend_refclassid,
812 Anum_pg_depend_refobjid,
816 {
818 Anum_pg_depend_refobjsubid,
822 }
823 else
830 {
838 /*
839 * If what we found is a sub-object of the current object, just ignore
840 * it. (Normally, such a dependency is implicit, but we must make
841 * explicit ones in some cases involving partitioning.)
842 */
848 /*
849 * Must lock the dependent object before recursing to it.
850 */
853 /*
854 * The dependent object might have been deleted while we waited to
855 * lock it; if so, we don't need to do anything more with it. We can
856 * test this cheaply and independently of the object's type by seeing
857 * if the pg_depend tuple we are looking at is still live. (If the
858 * object got deleted, the tuple would have been deleted too.)
859 */
861 {
862 /* release the now-useless lock */
864 /* and continue scanning for dependencies */
866 }
868 /*
869 * We do need to delete it, so identify objflags to be passed down,
870 * which depend on the dependency type.
871 */
873 {
896 }
898 /* And add it to the pending-objects list */
900 {
901 /* enlarge array if needed */
906 }
910 numDependentObjects++;
911 }
915 /*
916 * Now we can sort the dependent objects into a stable visitation order.
917 * It's safe to use object_address_comparator here since the obj field is
918 * first within ObjectAddressAndFlags.
919 */
923 object_address_comparator);
925 /*
926 * Now recurse to the dependent objects. We must visit them first since
927 * they have to be deleted before the current object.
928 */
934 {
939 flags,
941 targetObjects,
942 pendingObjects,
943 depRel);
944 }
948 /*
949 * Finally, we can add the target object to targetObjects. Be careful to
950 * include any flags that were passed back down to us from inner recursion
951 * levels. Record the "dependee" as being either the most important
952 * partition owner if there is one, else the object we recursed from, if
953 * any. (The logic in reportDependentObjects() is such that it can only
954 * need one of those objects.)
955 */
961 else
964 }
966 /*
967 * reportDependentObjects - report about dependencies, and fail if RESTRICT
968 *
969 * Tell the user about dependent objects that we are going to delete
970 * (or would need to delete, but are prevented by RESTRICT mode);
971 * then error out if there are any and it's not CASCADE mode.
972 *
973 * targetObjects: list of objects that are scheduled to be deleted
974 * behavior: RESTRICT or CASCADE
975 * flags: other flags for the deletion operation
976 * origObject: base object of deletion, or NULL if not available
977 * (the latter case occurs in DROP OWNED)
978 */
979 static void
981 DropBehavior behavior,
984 {
987 StringInfoData clientdetail;
988 StringInfoData logdetail;
993 /*
994 * If we need to delete any partition-dependent objects, make sure that
995 * we're deleting at least one of their partition dependencies, too. That
996 * can be detected by checking that we reached them by a PARTITION
997 * dependency at some point.
998 *
999 * We just report the first such object, as in most cases the only way to
1000 * trigger this complaint is to explicitly try to delete one partition of
1001 * a partitioned object.
1002 */
1004 {
1009 {
1019 }
1020 }
1022 /*
1023 * If no error is to be thrown, and the msglevel is too low to be shown to
1024 * either client or server log, there's no need to do any of the rest of
1025 * the work.
1026 */
1031 /*
1032 * We limit the number of dependencies reported to the client to
1033 * MAX_REPORTED_DEPS, since client software may not deal well with
1034 * enormous error strings. The server log always gets a full report.
1035 */
1036 #define MAX_REPORTED_DEPS 100
1041 /*
1042 * We process the list back to front (ie, in dependency order not deletion
1043 * order), since this makes for a more understandable display.
1044 */
1046 {
1051 /* Ignore the original deletion target(s) */
1055 /* Also ignore sub-objects; we'll report the whole object elsewhere */
1061 /* An object being dropped concurrently doesn't need to be reported */
1065 /*
1066 * If, at any stage of the recursive search, we reached the object via
1067 * an AUTO, INTERNAL, PARTITION, or EXTENSION dependency, then it's
1068 * okay to delete it even in RESTRICT mode.
1069 */
1071 DEPFLAG_INTERNAL |
1072 DEPFLAG_PARTITION |
1073 DEPFLAG_EXTENSION))
1074 {
1075 /*
1076 * auto-cascades are reported at DEBUG2, not msglevel. We don't
1077 * try to combine them with the regular message because the
1078 * results are too confusing when client_min_messages and
1079 * log_min_messages are different.
1080 */
1083 objDesc)));
1084 }
1086 {
1091 {
1093 {
1094 /* separate entries with a newline */
1099 numReportedClient++;
1100 }
1101 else
1102 numNotReportedClient++;
1103 /* separate entries with a newline */
1109 }
1110 else
1111 numNotReportedClient++;
1113 }
1114 else
1115 {
1117 {
1118 /* separate entries with a newline */
1122 objDesc);
1123 numReportedClient++;
1124 }
1125 else
1126 numNotReportedClient++;
1127 /* separate entries with a newline */
1131 objDesc);
1132 }
1135 }
1142 numNotReportedClient),
1143 numNotReportedClient);
1146 {
1155 else
1162 }
1164 {
1172 }
1174 {
1175 /* we just use the single item as-is */
1178 }
1182 }
1184 /*
1185 * Drop an object by OID. Works for most catalogs, if no special processing
1186 * is needed.
1187 */
1188 static void
1190 {
1192 Relation rel;
1193 HeapTuple tup;
1199 /*
1200 * Use the system cache for the oid column, if one exists.
1201 */
1203 {
1212 }
1213 else
1214 {
1216 SysScanDesc scan;
1226 /* we expect exactly one match */
1235 }
1238 }
1240 /*
1241 * deleteOneObject: delete a single object for performDeletion.
1242 *
1243 * *depRel is the already-open pg_depend relation.
1244 */
1245 static void
1247 {
1250 SysScanDesc scan;
1251 HeapTuple tup;
1253 /* DROP hook of the objects being removed */
1257 /*
1258 * Close depRel if we are doing a drop concurrently. The object deletion
1259 * subroutine will commit the current transaction, so we can't keep the
1260 * relation open across doDeletion().
1261 */
1265 /*
1266 * Delete the object itself, in an object-type-dependent way.
1267 *
1268 * We used to do this after removing the outgoing dependency links, but it
1269 * seems just as reasonable to do it beforehand. In the concurrent case
1270 * we *must* do it in this order, because we can't make any transactional
1271 * updates before calling doDeletion() --- they'd get committed right
1272 * away, which is not cool if the deletion then fails.
1273 */
1276 /*
1277 * Reopen depRel if we closed it above
1278 */
1282 /*
1283 * Now remove any pg_depend records that link from this object to others.
1284 * (Any records linking to this object should be gone already.)
1285 *
1286 * When dropping a whole object (subId = 0), remove all pg_depend records
1287 * for its sub-objects too.
1288 */
1290 Anum_pg_depend_classid,
1294 Anum_pg_depend_objid,
1298 {
1300 Anum_pg_depend_objsubid,
1304 }
1305 else
1312 {
1314 }
1318 /*
1319 * Delete shared dependency references related to this object. Again, if
1320 * subId = 0, remove records for sub-objects too.
1321 */
1326 /*
1327 * Delete any comments, security labels, or initial privileges associated
1328 * with this object. (This is a convenient place to do these things,
1329 * rather than having every object type know to do it.) As above, all
1330 * these functions must remove records for sub-objects too if the subid is
1331 * zero.
1332 */
1337 /*
1338 * CommandCounterIncrement here to ensure that preceding changes are all
1339 * visible to the next deletion step.
1340 */
1343 /*
1344 * And we're done!
1345 */
1346 }
1348 /*
1349 * doDeletion: actually delete a single object
1350 */
1351 static void
1353 {
1355 {
1357 {
1362 {
1368 }
1369 else
1370 {
1374 else
1376 }
1378 /*
1379 * for a sequence, in addition to dropping the heap, also
1380 * delete pg_sequence tuple
1381 */
1385 }
1470 /*
1471 * These global object types are not supported here.
1472 */
1483 }
1484 }
1486 /*
1487 * AcquireDeletionLock - acquire a suitable lock for deleting an object
1488 *
1489 * Accepts the same flags as performDeletion (though currently only
1490 * PERFORM_DELETION_CONCURRENTLY does anything).
1491 *
1492 * We use LockRelation for relations, and otherwise LockSharedObject or
1493 * LockDatabaseObject as appropriate for the object type.
1494 */
1495 void
1497 {
1499 {
1500 /*
1501 * In DROP INDEX CONCURRENTLY, take only ShareUpdateExclusiveLock on
1502 * the index for the moment. index_drop() will promote the lock once
1503 * it's safe to do so. In all other cases we need full exclusive
1504 * lock.
1505 */
1508 else
1510 }
1513 AccessExclusiveLock);
1514 else
1515 {
1516 /* assume we should lock the whole object not a sub-object */
1518 AccessExclusiveLock);
1519 }
1520 }
1522 /*
1523 * ReleaseDeletionLock - release an object deletion lock
1524 *
1525 * Companion to AcquireDeletionLock.
1526 */
1527 void
1529 {
1532 else
1533 /* assume we should lock the whole object not a sub-object */
1535 AccessExclusiveLock);
1536 }
1538 /*
1539 * recordDependencyOnExpr - find expression dependencies
1540 *
1541 * This is used to find the dependencies of rules, constraint expressions,
1542 * etc.
1543 *
1544 * Given an expression or query in node-tree form, find all the objects
1545 * it refers to (tables, columns, operators, functions, etc). Record
1546 * a dependency of the specified type from the given depender object
1547 * to each object mentioned in the expression.
1548 *
1549 * rtable is the rangetable to be used to interpret Vars with varlevelsup=0.
1550 * It can be NIL if no such variables are expected.
1551 */
1552 void
1555 DependencyType behavior)
1556 {
1557 find_expr_references_context context;
1561 /* Set up interpretation for Vars at varlevelsup = 0 */
1564 /* Scan the expression tree for referenceable objects */
1567 /* Remove any duplicates */
1570 /* And record 'em */
1573 behavior);
1576 }
1578 /*
1579 * recordDependencyOnSingleRelExpr - find expression dependencies
1580 *
1581 * As above, but only one relation is expected to be referenced (with
1582 * varno = 1 and varlevelsup = 0). Pass the relation OID instead of a
1583 * range table. An additional frammish is that dependencies on that
1584 * relation's component columns will be marked with 'self_behavior',
1585 * whereas 'behavior' is used for everything else; also, if 'reverse_self'
1586 * is true, those dependencies are reversed so that the columns are made
1587 * to depend on the table not vice versa.
1588 *
1589 * NOTE: the caller should ensure that a whole-table dependency on the
1590 * specified relation is created separately, if one is needed. In particular,
1591 * a whole-row Var "relation.*" will not cause this routine to emit any
1592 * dependency item. This is appropriate behavior for subexpressions of an
1593 * ordinary query, so other cases need to cope as necessary.
1594 */
1595 void
1598 DependencyType behavior,
1599 DependencyType self_behavior,
1601 {
1602 find_expr_references_context context;
1607 /* We gin up a rather bogus rangetable list to handle Vars */
1616 /* Scan the expression tree for referenceable objects */
1619 /* Remove any duplicates */
1622 /* Separate self-dependencies if necessary */
1625 {
1629 outrefs;
1636 {
1641 {
1642 /* Move this ref into self_addrs */
1644 }
1645 else
1646 {
1647 /* Keep it in context.addrs */
1649 outobj++;
1650 outrefs++;
1651 }
1652 }
1655 /* Record the self-dependencies with the appropriate direction */
1659 self_behavior);
1660 else
1661 {
1662 /* Can't use recordMultipleDependencies, so do it the hard way */
1666 {
1670 }
1671 }
1674 }
1676 /* Record the external dependencies */
1679 behavior);
1682 }
1684 /*
1685 * Recursively search an expression tree for object references.
1686 *
1687 * Note: in many cases we do not need to create dependencies on the datatypes
1688 * involved in an expression, because we'll have an indirect dependency via
1689 * some other object. For instance Var nodes depend on a column which depends
1690 * on the datatype, and OpExpr nodes depend on the operator which depends on
1691 * the datatype. However we do need a type dependency if there is no such
1692 * indirect dependency, as for example in Const and CoerceToDomain nodes.
1693 *
1694 * Similarly, we don't need to create dependencies on collations except where
1695 * the collation is being freshly introduced to the expression.
1696 */
1697 static bool
1700 {
1704 {
1709 /* Find matching rtable entry, or complain if not found */
1717 /*
1718 * A whole-row Var references no specific columns, so adds no new
1719 * dependency. (We assume that there is a whole-table dependency
1720 * arising from each underlying rangetable entry. While we could
1721 * record such a dependency when finding a whole-row Var that
1722 * references a relation directly, it's quite unclear how to extend
1723 * that to whole-row Vars for JOINs, so it seems better to leave the
1724 * responsibility with the range table. Note that this poses some
1725 * risks for identifying dependencies of stand-alone expressions:
1726 * whole-table references may need to be created separately.)
1727 */
1731 {
1732 /* If it's a plain relation, reference this column */
1735 }
1737 {
1738 /* Might need to add a dependency on a composite type's column */
1739 /* (done out of line, because it's a bit bulky) */
1741 }
1743 /*
1744 * Vars referencing other RTE types require no additional work. In
1745 * particular, a join alias Var can be ignored, because it must
1746 * reference a merged USING column. The relevant join input columns
1747 * will also be referenced in the join qual, and any type coercion
1748 * functions involved in the alias expression will be dealt with when
1749 * we scan the RTE itself.
1750 */
1752 }
1754 {
1756 Oid objoid;
1758 /* A constant must depend on the constant's datatype */
1762 /*
1763 * We must also depend on the constant's collation: it could be
1764 * different from the datatype's, if a CollateExpr was const-folded to
1765 * a simple constant. However we can save work in the most common
1766 * case where the collation is "default", since we know that's pinned.
1767 */
1773 /*
1774 * If it's a regclass or similar literal referring to an existing
1775 * object, add a reference to that object. (Currently, only the
1776 * regclass and regconfig cases have any likely use, but we may as
1777 * well handle all the OID-alias datatypes consistently.)
1778 */
1780 {
1782 {
1843 /*
1844 * Dependencies for regrole should be shared among all
1845 * databases, so explicitly inhibit to have dependencies.
1846 */
1853 }
1854 }
1856 }
1858 {
1861 /* A parameter must depend on the parameter's datatype */
1864 /* and its collation, just as for Consts */
1869 }
1871 {
1876 /* fall through to examine arguments */
1877 }
1879 {
1884 /* fall through to examine arguments */
1885 }
1887 {
1892 /* fall through to examine arguments */
1893 }
1895 {
1900 /* fall through to examine arguments */
1901 }
1903 {
1908 /* fall through to examine arguments */
1909 }
1911 {
1916 /* fall through to examine arguments */
1917 }
1919 {
1924 /* fall through to examine arguments */
1925 }
1927 {
1930 /*
1931 * The refexpr should provide adequate dependency on refcontainertype,
1932 * and that type in turn depends on refelemtype. However, a custom
1933 * subscripting handler might set refrestype to something different
1934 * from either of those, in which case we'd better record it.
1935 */
1940 /* fall through to examine arguments */
1941 }
1943 {
1944 /* Extra work needed here if we ever need this case */
1946 }
1948 {
1953 /*
1954 * We need a dependency on the specific column named in FieldSelect,
1955 * assuming we can identify the pg_class OID for it. (Probably we
1956 * always can at the moment, but in future it might be possible for
1957 * argtype to be RECORDOID.) If we can make a column dependency then
1958 * we shouldn't need a dependency on the column's type; but if we
1959 * can't, make a dependency on the type, as it might not appear
1960 * anywhere else in the expression.
1961 */
1965 else
1968 /* the collation might not be referenced anywhere else, either */
1973 }
1975 {
1979 /* similar considerations to FieldSelect, but multiple column(s) */
1981 {
1987 }
1988 else
1991 }
1993 {
1996 /* since there is no function dependency, need to depend on type */
1999 /* the collation might not be referenced anywhere else, either */
2004 }
2006 {
2009 /* since there is no exposed function, need to depend on type */
2012 /* the collation might not be referenced anywhere else, either */
2017 }
2019 {
2022 /* as above, depend on type */
2025 /* the collation might not be referenced anywhere else, either */
2030 /* fall through to examine arguments */
2031 }
2033 {
2036 /* since there is no function dependency, need to depend on type */
2039 }
2041 {
2046 }
2048 {
2053 }
2055 {
2060 {
2063 }
2065 {
2068 }
2069 /* fall through to examine arguments */
2070 }
2072 {
2077 }
2079 {
2084 }
2086 {
2092 /* fall through to examine arguments */
2093 }
2095 {
2104 }
2106 {
2119 /* fall through to examine substructure */
2120 }
2122 {
2134 /* fall through to examine substructure */
2135 }
2137 {
2138 /* Recurse into RTE subquery or not-yet-planned sublink subquery */
2143 /*
2144 * Add whole-relation refs for each plain relation mentioned in the
2145 * subquery's rtable, and ensure we add refs for any type-coercion
2146 * functions used in join alias lists.
2147 *
2148 * Note: query_tree_walker takes care of recursing into RTE_FUNCTION
2149 * RTEs, subqueries, etc, so no need to do that here. But we must
2150 * tell it not to visit join alias lists, or we'll add refs for join
2151 * input columns whether or not they are actually used in our query.
2152 *
2153 * Note: we don't need to worry about collations mentioned in
2154 * RTE_VALUES or RTE_CTE RTEs, because those must just duplicate
2155 * collations referenced in other parts of the Query. We do have to
2156 * worry about collations mentioned in RTE_FUNCTION, but we take care
2157 * of those when we recurse to the RangeTblFunction node(s).
2158 */
2160 {
2164 {
2171 /*
2172 * Examine joinaliasvars entries only for merged JOIN
2173 * USING columns. Only those entries could contain
2174 * type-coercion functions. Also, their join input
2175 * columns must be referenced in the join quals, so this
2176 * won't accidentally add refs to otherwise-unused join
2177 * input columns. (We want to ref the type coercion
2178 * functions even if the merged column isn't explicitly
2179 * used anywhere, to protect possible expansion of the
2180 * join RTE as a whole-row var, and because it seems like
2181 * a bad idea to allow dropping a function that's present
2182 * in our query tree, whether or not it could get called.)
2183 */
2186 {
2191 }
2196 }
2197 }
2199 /*
2200 * If the query is an INSERT or UPDATE, we should create a dependency
2201 * on each target column, to prevent the specific target column from
2202 * being dropped. Although we will visit the TargetEntry nodes again
2203 * during query_tree_walker, we won't have enough context to do this
2204 * conveniently, so do it here.
2205 */
2208 {
2217 {
2219 {
2226 }
2227 }
2228 }
2230 /*
2231 * Add dependencies on constraints listed in query's constraintDeps
2232 */
2234 {
2237 }
2239 /* Examine substructure of query */
2242 find_expr_references_walker,
2243 context,
2244 QTW_IGNORE_JOINALIASES |
2245 QTW_EXAMINE_SORTGROUP);
2248 }
2250 {
2253 /* we need to look at the groupClauses for operator references */
2255 /* fall through to examine child nodes */
2256 }
2258 {
2262 /*
2263 * Add refs for any datatypes and collations used in a column
2264 * definition list for a RECORD function. (For other cases, it should
2265 * be enough to depend on the function itself.)
2266 */
2268 {
2271 }
2273 {
2279 }
2280 }
2282 {
2286 /*
2287 * Add refs for the datatypes and collations used in the TableFunc.
2288 */
2290 {
2293 }
2295 {
2301 }
2302 }
2304 {
2309 /* fall through to examine arguments */
2310 }
2313 context);
2314 }
2316 /*
2317 * find_expr_references_walker subroutine: handle a Var reference
2318 * to an RTE_FUNCTION RTE
2319 */
2320 static void
2323 {
2327 /*
2328 * Identify which RangeTblFunction produces this attnum, and see if it
2329 * returns a composite type. If so, we'd better make a dependency on the
2330 * referenced column of the composite type (or actually, of its associated
2331 * relation).
2332 */
2334 {
2339 {
2340 TupleDesc tupdesc;
2342 /* If it has a coldeflist, it certainly returns RECORD */
2345 else
2348 {
2349 /*
2350 * Named composite type, so individual columns could get
2351 * dropped. Make a dependency on this specific column.
2352 */
2361 }
2362 /* Nothing to do; function's result type is handled elsewhere */
2364 }
2366 }
2368 /* If we get here, must be looking for the ordinality column */
2372 /* this probably can't happen ... */
2377 }
2379 /*
2380 * Given an array of dependency references, eliminate any duplicates.
2381 */
2382 static void
2384 {
2387 newrefs;
2389 /*
2390 * We can't sort if the array has "extra" data, because there's no way to
2391 * keep it in sync. Fortunately that combination of features is not
2392 * needed.
2393 */
2399 /* Sort the refs so that duplicates are adjacent */
2401 object_address_comparator);
2403 /* Remove dups */
2407 {
2412 {
2416 /*
2417 * If we have a whole-object reference and a reference to a part
2418 * of the same object, we don't need the whole-object reference
2419 * (for example, we don't need to reference both table foo and
2420 * column foo.bar). The whole-object reference will always appear
2421 * first in the sorted list.
2422 */
2424 {
2425 /* replace whole ref with partial */
2428 }
2429 }
2430 /* Not identical, so add thisobj to output set */
2431 priorobj++;
2433 newrefs++;
2434 }
2437 }
2439 /*
2440 * qsort comparator for ObjectAddress items
2441 */
2442 static int
2444 {
2448 /*
2449 * Primary sort key is OID descending. Most of the time, this will result
2450 * in putting newer objects before older ones, which is likely to be the
2451 * right order to delete in.
2452 */
2458 /*
2459 * Next sort on catalog ID, in case identical OIDs appear in different
2460 * catalogs. Sort direction is pretty arbitrary here.
2461 */
2467 /*
2468 * Last, sort on object subId.
2469 *
2470 * We sort the subId as an unsigned int so that 0 (the whole object) will
2471 * come first. This is essential for eliminate_duplicate_dependencies,
2472 * and is also the best order for findDependentObjects.
2473 */
2479 }
2481 /*
2482 * Routines for handling an expansible array of ObjectAddress items.
2483 *
2484 * new_object_addresses: create a new ObjectAddresses array.
2485 */
2486 ObjectAddresses *
2488 {
2500 }
2502 /*
2503 * Add an entry to an ObjectAddresses array.
2504 */
2505 static void
2508 {
2511 /* enlarge array if needed */
2513 {
2518 }
2519 /* record this item */
2525 }
2527 /*
2528 * Add an entry to an ObjectAddresses array.
2529 *
2530 * As above, but specify entry exactly.
2531 */
2532 void
2535 {
2538 /* enlarge array if needed */
2540 {
2545 }
2546 /* record this item */
2550 }
2552 /*
2553 * Add an entry to an ObjectAddresses array.
2554 *
2555 * As above, but specify entry exactly and provide some "extra" data too.
2556 */
2557 static void
2561 {
2565 /* allocate extra space if first time */
2570 /* enlarge array if needed */
2572 {
2578 }
2579 /* record this item */
2585 }
2587 /*
2588 * Test whether an object is present in an ObjectAddresses array.
2589 *
2590 * We return "true" if object is a subobject of something in the array, too.
2591 */
2592 bool
2595 {
2599 {
2604 {
2608 }
2609 }
2612 }
2614 /*
2615 * As above, except that if the object is present then also OR the given
2616 * flags into its associated extra data (which must exist).
2617 */
2618 static bool
2622 {
2627 {
2632 {
2634 {
2639 }
2641 {
2642 /*
2643 * We get here if we find a need to delete a column after
2644 * having already decided to drop its whole table. Obviously
2645 * we no longer need to drop the subobject, so report that we
2646 * found the subobject in the array. But don't plaster its
2647 * flags on the whole object.
2648 */
2650 }
2652 {
2653 /*
2654 * We get here if we find a need to delete a whole table after
2655 * having already decided to drop one of its columns. We
2656 * can't report that the whole object is in the array, but we
2657 * should mark the subobject with the whole object's flags.
2658 *
2659 * It might seem attractive to physically delete the column's
2660 * array entry, or at least mark it as no longer needing
2661 * separate deletion. But that could lead to, e.g., dropping
2662 * the column's datatype before we drop the table, which does
2663 * not seem like a good idea. This is a very rare situation
2664 * in practice, so we just take the hit of doing a separate
2665 * DROP COLUMN action even though we know we're gonna delete
2666 * the table later.
2667 *
2668 * What we can do, though, is mark this as a subobject so that
2669 * we don't report it separately, which is confusing because
2670 * it's unpredictable whether it happens or not. But do so
2671 * only if flags != 0 (flags == 0 is a read-only probe).
2672 *
2673 * Because there could be other subobjects of this object in
2674 * the array, this case means we always have to loop through
2675 * the whole array; we cannot exit early on a match.
2676 */
2681 }
2682 }
2683 }
2686 }
2688 /*
2689 * Similar to above, except we search an ObjectAddressStack.
2690 */
2691 static bool
2695 {
2700 {
2705 {
2707 {
2710 }
2712 {
2713 /*
2714 * We're visiting a column with whole table already on stack.
2715 * As in object_address_present_add_flags(), we can skip
2716 * further processing of the subobject, but we don't want to
2717 * propagate flags for the subobject to the whole object.
2718 */
2720 }
2722 {
2723 /*
2724 * We're visiting a table with column already on stack. As in
2725 * object_address_present_add_flags(), we should propagate
2726 * flags for the whole object to each of its subobjects.
2727 */
2730 }
2731 }
2732 }
2735 }
2737 /*
2738 * Record multiple dependencies from an ObjectAddresses array, after first
2739 * removing any duplicates.
2740 */
2741 void
2744 DependencyType behavior)
2745 {
2749 behavior);
2750 }
2752 /*
2753 * Sort the items in an ObjectAddresses array.
2754 *
2755 * The major sort key is OID-descending, so that newer objects will be listed
2756 * first in most cases. This is primarily useful for ensuring stable outputs
2757 * from regression tests; it's not recommended if the order of the objects is
2758 * determined by user input, such as the order of targets in a DROP command.
2759 */
2760 void
2762 {
2766 object_address_comparator);
2767 }
2769 /*
2770 * Clean up when done with an ObjectAddresses array.
2771 */
2772 void
2774 {
2779 }
2781 /*
2782 * delete initial ACL for extension objects
2783 */
2784 static void
2786 {
2787 Relation relation;
2790 SysScanDesc scan;
2791 HeapTuple oldtuple;
2796 Anum_pg_init_privs_objoid,
2800 Anum_pg_init_privs_classoid,
2804 {
2806 Anum_pg_init_privs_objsubid,
2810 }
2811 else
2823 }