1 /*-------------------------------------------------------------------------
4 * routines for inserting index tuples and enforcing unique and
5 * exclusion constraints.
7 * ExecInsertIndexTuples() is the main entry point. It's called after
8 * inserting a tuple to the heap, and it inserts corresponding index tuples
9 * into all indexes. At the same time, it enforces any unique and
10 * exclusion constraints:
15 * Enforcing a unique constraint is straightforward. When the index AM
16 * inserts the tuple to the index, it also checks that there are no
17 * conflicting tuples in the index already. It does so atomically, so that
18 * even if two backends try to insert the same key concurrently, only one
19 * of them will succeed. All the logic to ensure atomicity, and to wait
20 * for in-progress transactions to finish, is handled by the index AM.
22 * If a unique constraint is deferred, we request the index AM to not
23 * throw an error if a conflict is found. Instead, we make note that there
24 * was a conflict and return the list of indexes with conflicts to the
25 * caller. The caller must re-check them later, by calling index_insert()
26 * with the UNIQUE_CHECK_EXISTING option.
28 * Exclusion Constraints
29 * ---------------------
31 * Exclusion constraints are different from unique indexes in that when the
32 * tuple is inserted to the index, the index AM does not check for
33 * duplicate keys at the same time. After the insertion, we perform a
34 * separate scan on the index to check for conflicting tuples, and if one
35 * is found, we throw an error and the transaction is aborted. If the
36 * conflicting tuple's inserter or deleter is in-progress, we wait for it
39 * There is a chance of deadlock, if two backends insert a tuple at the
40 * same time, and then perform the scan to check for conflicts. They will
41 * find each other's tuple, and both try to wait for each other. The
42 * deadlock detector will detect that, and abort one of the transactions.
43 * That's fairly harmless, as one of them was bound to abort with a
44 * "duplicate key error" anyway, although you get a different error
47 * If an exclusion constraint is deferred, we still perform the conflict
48 * checking scan immediately after inserting the index tuple. But instead
49 * of throwing an error if a conflict is found, we return that information
50 * to the caller. The caller must re-check them later by calling
51 * check_exclusion_constraint().
53 * Speculative insertion
54 * ---------------------
56 * Speculative insertion is a two-phase mechanism used to implement
57 * INSERT ... ON CONFLICT DO UPDATE/NOTHING. The tuple is first inserted
58 * to the heap and update the indexes as usual, but if a constraint is
59 * violated, we can still back out the insertion without aborting the whole
60 * transaction. In an INSERT ... ON CONFLICT statement, if a conflict is
61 * detected, the inserted tuple is backed out and the ON CONFLICT action is
64 * Insertion to a unique index works as usual: the index AM checks for
65 * duplicate keys atomically with the insertion. But instead of throwing
66 * an error on a conflict, the speculatively inserted heap tuple is backed
69 * Exclusion constraints are slightly more complicated. As mentioned
70 * earlier, there is a risk of deadlock when two backends insert the same
71 * key concurrently. That was not a problem for regular insertions, when
72 * one of the transactions has to be aborted anyway, but with a speculative
73 * insertion we cannot let a deadlock happen, because we only want to back
74 * out the speculatively inserted tuple on conflict, not abort the whole
77 * When a backend detects that the speculative insertion conflicts with
78 * another in-progress tuple, it has two options:
80 * 1. back out the speculatively inserted tuple, then wait for the other
81 * transaction, and retry. Or,
82 * 2. wait for the other transaction, with the speculatively inserted tuple
85 * If two backends insert at the same time, and both try to wait for each
86 * other, they will deadlock. So option 2 is not acceptable. Option 1
87 * avoids the deadlock, but it is prone to a livelock instead. Both
88 * transactions will wake up immediately as the other transaction backs
89 * out. Then they both retry, and conflict with each other again, lather,
92 * To avoid the livelock, one of the backends must back out first, and then
93 * wait, while the other one waits without backing out. It doesn't matter
94 * which one backs out, so we employ an arbitrary rule that the transaction
95 * with the higher XID backs out.
98 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
99 * Portions Copyright (c) 1994, Regents of the University of California
103 * src/backend/executor/execIndexing.c
105 *-------------------------------------------------------------------------
107 #include "postgres.h"
109 #include "access/relscan.h"
110 #include "access/xact.h"
111 #include "catalog/index.h"
112 #include "executor/executor.h"
113 #include "nodes/nodeFuncs.h"
114 #include "storage/lmgr.h"
115 #include "utils/tqual.h"
117 /* waitMode argument to check_exclusion_or_unique_constraint() */
122 CEOUC_LIVELOCK_PREVENTING_WAIT
125 static bool check_exclusion_or_unique_constraint(Relation heap, Relation index,
126 IndexInfo *indexInfo,
128 Datum *values, bool *isnull,
129 EState *estate, bool newIndex,
130 CEOUC_WAIT_MODE waitMode,
132 ItemPointer conflictTid);
134 static bool index_recheck_constraint(Relation index, Oid *constr_procs,
135 Datum *existing_values, bool *existing_isnull,
138 /* ----------------------------------------------------------------
141 * Find the indices associated with a result relation, open them,
142 * and save information about them in the result ResultRelInfo.
144 * At entry, caller has already opened and locked
145 * resultRelInfo->ri_RelationDesc.
146 * ----------------------------------------------------------------
149 ExecOpenIndices(ResultRelInfo *resultRelInfo, bool speculative)
151 Relation resultRelation = resultRelInfo->ri_RelationDesc;
156 RelationPtr relationDescs;
157 IndexInfo **indexInfoArray;
159 resultRelInfo->ri_NumIndices = 0;
161 /* fast path if no indexes */
162 if (!RelationGetForm(resultRelation)->relhasindex)
166 * Get cached list of index OIDs
168 indexoidlist = RelationGetIndexList(resultRelation);
169 len = list_length(indexoidlist);
174 * allocate space for result arrays
176 relationDescs = (RelationPtr) palloc(len * sizeof(Relation));
177 indexInfoArray = (IndexInfo **) palloc(len * sizeof(IndexInfo *));
179 resultRelInfo->ri_NumIndices = len;
180 resultRelInfo->ri_IndexRelationDescs = relationDescs;
181 resultRelInfo->ri_IndexRelationInfo = indexInfoArray;
184 * For each index, open the index relation and save pg_index info. We
185 * acquire RowExclusiveLock, signifying we will update the index.
187 * Note: we do this even if the index is not IndexIsReady; it's not worth
188 * the trouble to optimize for the case where it isn't.
191 foreach(l, indexoidlist)
193 Oid indexOid = lfirst_oid(l);
197 indexDesc = index_open(indexOid, RowExclusiveLock);
199 /* extract index key information from the index's pg_index info */
200 ii = BuildIndexInfo(indexDesc);
203 * If the indexes are to be used for speculative insertion, add extra
204 * information required by unique index entries.
206 if (speculative && ii->ii_Unique)
207 BuildSpeculativeIndexInfo(indexDesc, ii);
209 relationDescs[i] = indexDesc;
210 indexInfoArray[i] = ii;
214 list_free(indexoidlist);
217 /* ----------------------------------------------------------------
220 * Close the index relations stored in resultRelInfo
221 * ----------------------------------------------------------------
224 ExecCloseIndices(ResultRelInfo *resultRelInfo)
228 RelationPtr indexDescs;
230 numIndices = resultRelInfo->ri_NumIndices;
231 indexDescs = resultRelInfo->ri_IndexRelationDescs;
233 for (i = 0; i < numIndices; i++)
235 if (indexDescs[i] == NULL)
236 continue; /* shouldn't happen? */
238 /* Drop lock acquired by ExecOpenIndices */
239 index_close(indexDescs[i], RowExclusiveLock);
243 * XXX should free indexInfo array here too? Currently we assume that
244 * such stuff will be cleaned up automatically in FreeExecutorState.
248 /* ----------------------------------------------------------------
249 * ExecInsertIndexTuples
251 * This routine takes care of inserting index tuples
252 * into all the relations indexing the result relation
253 * when a heap tuple is inserted into the result relation.
255 * Unique and exclusion constraints are enforced at the same
256 * time. This returns a list of index OIDs for any unique or
257 * exclusion constraints that are deferred and that had
258 * potential (unconfirmed) conflicts. (if noDupErr == true,
259 * the same is done for non-deferred constraints, but report
260 * if conflict was speculative or deferred conflict to caller)
262 * If 'arbiterIndexes' is nonempty, noDupErr applies only to
263 * those indexes. NIL means noDupErr applies to all indexes.
265 * CAUTION: this must not be called for a HOT update.
266 * We can't defend against that here for lack of info.
267 * Should we change the API to make it safer?
268 * ----------------------------------------------------------------
271 ExecInsertIndexTuples(TupleTableSlot *slot,
276 List *arbiterIndexes)
279 ResultRelInfo *resultRelInfo;
282 RelationPtr relationDescs;
283 Relation heapRelation;
284 IndexInfo **indexInfoArray;
285 ExprContext *econtext;
286 Datum values[INDEX_MAX_KEYS];
287 bool isnull[INDEX_MAX_KEYS];
290 * Get information from the result relation info structure.
292 resultRelInfo = estate->es_result_relation_info;
293 numIndices = resultRelInfo->ri_NumIndices;
294 relationDescs = resultRelInfo->ri_IndexRelationDescs;
295 indexInfoArray = resultRelInfo->ri_IndexRelationInfo;
296 heapRelation = resultRelInfo->ri_RelationDesc;
299 * We will use the EState's per-tuple context for evaluating predicates
300 * and index expressions (creating it if it's not already there).
302 econtext = GetPerTupleExprContext(estate);
304 /* Arrange for econtext's scan tuple to be the tuple under test */
305 econtext->ecxt_scantuple = slot;
308 * for each index, form and insert the index tuple
310 for (i = 0; i < numIndices; i++)
312 Relation indexRelation = relationDescs[i];
313 IndexInfo *indexInfo;
315 IndexUniqueCheck checkUnique;
316 bool satisfiesConstraint;
318 if (indexRelation == NULL)
321 indexInfo = indexInfoArray[i];
323 /* If the index is marked as read-only, ignore it */
324 if (!indexInfo->ii_ReadyForInserts)
327 /* Check for partial index */
328 if (indexInfo->ii_Predicate != NIL)
333 * If predicate state not set up yet, create it (in the estate's
336 predicate = indexInfo->ii_PredicateState;
337 if (predicate == NIL)
340 ExecPrepareExpr((Expr *) indexInfo->ii_Predicate,
342 indexInfo->ii_PredicateState = predicate;
345 /* Skip this index-update if the predicate isn't satisfied */
346 if (!ExecQual(predicate, econtext, false))
351 * FormIndexDatum fills in its values and isnull parameters with the
352 * appropriate values for the column(s) of the index.
354 FormIndexDatum(indexInfo,
360 /* Check whether to apply noDupErr to this index */
361 applyNoDupErr = noDupErr &&
362 (arbiterIndexes == NIL ||
363 list_member_oid(arbiterIndexes,
364 indexRelation->rd_index->indexrelid));
367 * The index AM does the actual insertion, plus uniqueness checking.
369 * For an immediate-mode unique index, we just tell the index AM to
370 * throw error if not unique.
372 * For a deferrable unique index, we tell the index AM to just detect
373 * possible non-uniqueness, and we add the index OID to the result
374 * list if further checking is needed.
376 * For a speculative insertion (used by INSERT ... ON CONFLICT), do
377 * the same as for a deferrable unique index.
379 if (!indexRelation->rd_index->indisunique)
380 checkUnique = UNIQUE_CHECK_NO;
381 else if (applyNoDupErr)
382 checkUnique = UNIQUE_CHECK_PARTIAL;
383 else if (indexRelation->rd_index->indimmediate)
384 checkUnique = UNIQUE_CHECK_YES;
386 checkUnique = UNIQUE_CHECK_PARTIAL;
388 satisfiesConstraint =
389 index_insert(indexRelation, /* index relation */
390 values, /* array of index Datums */
391 isnull, /* null flags */
392 tupleid, /* tid of heap tuple */
393 heapRelation, /* heap relation */
394 checkUnique); /* type of uniqueness check to do */
397 * If the index has an associated exclusion constraint, check that.
398 * This is simpler than the process for uniqueness checks since we
399 * always insert first and then check. If the constraint is deferred,
400 * we check now anyway, but don't throw error on violation or wait for
401 * a conclusive outcome from a concurrent insertion; instead we'll
402 * queue a recheck event. Similarly, noDupErr callers (speculative
403 * inserters) will recheck later, and wait for a conclusive outcome
406 * An index for an exclusion constraint can't also be UNIQUE (not an
407 * essential property, we just don't allow it in the grammar), so no
408 * need to preserve the prior state of satisfiesConstraint.
410 if (indexInfo->ii_ExclusionOps != NULL)
413 CEOUC_WAIT_MODE waitMode;
418 waitMode = CEOUC_LIVELOCK_PREVENTING_WAIT;
420 else if (!indexRelation->rd_index->indimmediate)
423 waitMode = CEOUC_NOWAIT;
428 waitMode = CEOUC_WAIT;
431 satisfiesConstraint =
432 check_exclusion_or_unique_constraint(heapRelation,
433 indexRelation, indexInfo,
434 tupleid, values, isnull,
436 waitMode, violationOK, NULL);
439 if ((checkUnique == UNIQUE_CHECK_PARTIAL ||
440 indexInfo->ii_ExclusionOps != NULL) &&
441 !satisfiesConstraint)
444 * The tuple potentially violates the uniqueness or exclusion
445 * constraint, so make a note of the index so that we can re-check
446 * it later. Speculative inserters are told if there was a
447 * speculative conflict, since that always requires a restart.
449 result = lappend_oid(result, RelationGetRelid(indexRelation));
450 if (indexRelation->rd_index->indimmediate && specConflict)
451 *specConflict = true;
458 /* ----------------------------------------------------------------
459 * ExecCheckIndexConstraints
461 * This routine checks if a tuple violates any unique or
462 * exclusion constraints. Returns true if there is no conflict.
463 * Otherwise returns false, and the TID of the conflicting
464 * tuple is returned in *conflictTid.
466 * If 'arbiterIndexes' is given, only those indexes are checked.
467 * NIL means all indexes.
469 * Note that this doesn't lock the values in any way, so it's
470 * possible that a conflicting tuple is inserted immediately
471 * after this returns. But this can be used for a pre-check
473 * ----------------------------------------------------------------
476 ExecCheckIndexConstraints(TupleTableSlot *slot,
477 EState *estate, ItemPointer conflictTid,
478 List *arbiterIndexes)
480 ResultRelInfo *resultRelInfo;
483 RelationPtr relationDescs;
484 Relation heapRelation;
485 IndexInfo **indexInfoArray;
486 ExprContext *econtext;
487 Datum values[INDEX_MAX_KEYS];
488 bool isnull[INDEX_MAX_KEYS];
489 ItemPointerData invalidItemPtr;
490 bool checkedIndex = false;
492 ItemPointerSetInvalid(conflictTid);
493 ItemPointerSetInvalid(&invalidItemPtr);
496 * Get information from the result relation info structure.
498 resultRelInfo = estate->es_result_relation_info;
499 numIndices = resultRelInfo->ri_NumIndices;
500 relationDescs = resultRelInfo->ri_IndexRelationDescs;
501 indexInfoArray = resultRelInfo->ri_IndexRelationInfo;
502 heapRelation = resultRelInfo->ri_RelationDesc;
505 * We will use the EState's per-tuple context for evaluating predicates
506 * and index expressions (creating it if it's not already there).
508 econtext = GetPerTupleExprContext(estate);
510 /* Arrange for econtext's scan tuple to be the tuple under test */
511 econtext->ecxt_scantuple = slot;
514 * For each index, form index tuple and check if it satisfies the
517 for (i = 0; i < numIndices; i++)
519 Relation indexRelation = relationDescs[i];
520 IndexInfo *indexInfo;
521 bool satisfiesConstraint;
523 if (indexRelation == NULL)
526 indexInfo = indexInfoArray[i];
528 if (!indexInfo->ii_Unique && !indexInfo->ii_ExclusionOps)
531 /* If the index is marked as read-only, ignore it */
532 if (!indexInfo->ii_ReadyForInserts)
535 /* When specific arbiter indexes requested, only examine them */
536 if (arbiterIndexes != NIL &&
537 !list_member_oid(arbiterIndexes,
538 indexRelation->rd_index->indexrelid))
541 if (!indexRelation->rd_index->indimmediate)
543 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
544 errmsg("ON CONFLICT does not support deferrable unique constraints/exclusion constraints as arbiters"),
545 errtableconstraint(heapRelation,
546 RelationGetRelationName(indexRelation))));
550 /* Check for partial index */
551 if (indexInfo->ii_Predicate != NIL)
556 * If predicate state not set up yet, create it (in the estate's
559 predicate = indexInfo->ii_PredicateState;
560 if (predicate == NIL)
563 ExecPrepareExpr((Expr *) indexInfo->ii_Predicate,
565 indexInfo->ii_PredicateState = predicate;
568 /* Skip this index-update if the predicate isn't satisfied */
569 if (!ExecQual(predicate, econtext, false))
574 * FormIndexDatum fills in its values and isnull parameters with the
575 * appropriate values for the column(s) of the index.
577 FormIndexDatum(indexInfo,
583 satisfiesConstraint =
584 check_exclusion_or_unique_constraint(heapRelation, indexRelation,
585 indexInfo, &invalidItemPtr,
586 values, isnull, estate, false,
589 if (!satisfiesConstraint)
593 if (arbiterIndexes != NIL && !checkedIndex)
594 elog(ERROR, "unexpected failure to find arbiter index");
600 * Check for violation of an exclusion or unique constraint
602 * heap: the table containing the new tuple
603 * index: the index supporting the constraint
604 * indexInfo: info about the index, including the exclusion properties
605 * tupleid: heap TID of the new tuple we have just inserted (invalid if we
606 * haven't inserted a new tuple yet)
607 * values, isnull: the *index* column values computed for the new tuple
608 * estate: an EState we can do evaluation in
609 * newIndex: if true, we are trying to build a new index (this affects
610 * only the wording of error messages)
611 * waitMode: whether to wait for concurrent inserters/deleters
612 * violationOK: if true, don't throw error for violation
613 * conflictTid: if not-NULL, the TID of the conflicting tuple is returned here
615 * Returns true if OK, false if actual or potential violation
617 * 'waitMode' determines what happens if a conflict is detected with a tuple
618 * that was inserted or deleted by a transaction that's still running.
619 * CEOUC_WAIT means that we wait for the transaction to commit, before
620 * throwing an error or returning. CEOUC_NOWAIT means that we report the
621 * violation immediately; so the violation is only potential, and the caller
622 * must recheck sometime later. This behavior is convenient for deferred
623 * exclusion checks; we need not bother queuing a deferred event if there is
624 * definitely no conflict at insertion time.
626 * CEOUC_LIVELOCK_PREVENTING_WAIT is like CEOUC_NOWAIT, but we will sometimes
627 * wait anyway, to prevent livelocking if two transactions try inserting at
628 * the same time. This is used with speculative insertions, for INSERT ON
629 * CONFLICT statements. (See notes in file header)
631 * If violationOK is true, we just report the potential or actual violation to
632 * the caller by returning 'false'. Otherwise we throw a descriptive error
633 * message here. When violationOK is false, a false result is impossible.
635 * Note: The indexam is normally responsible for checking unique constraints,
636 * so this normally only needs to be used for exclusion constraints. But this
637 * function is also called when doing a "pre-check" for conflicts on a unique
638 * constraint, when doing speculative insertion. Caller may use the returned
639 * conflict TID to take further steps.
642 check_exclusion_or_unique_constraint(Relation heap, Relation index,
643 IndexInfo *indexInfo,
645 Datum *values, bool *isnull,
646 EState *estate, bool newIndex,
647 CEOUC_WAIT_MODE waitMode,
649 ItemPointer conflictTid)
652 uint16 *constr_strats;
653 Oid *index_collations = index->rd_indcollation;
654 int index_natts = index->rd_index->indnatts;
655 IndexScanDesc index_scan;
657 ScanKeyData scankeys[INDEX_MAX_KEYS];
658 SnapshotData DirtySnapshot;
662 ExprContext *econtext;
663 TupleTableSlot *existing_slot;
664 TupleTableSlot *save_scantuple;
666 if (indexInfo->ii_ExclusionOps)
668 constr_procs = indexInfo->ii_ExclusionProcs;
669 constr_strats = indexInfo->ii_ExclusionStrats;
673 constr_procs = indexInfo->ii_UniqueProcs;
674 constr_strats = indexInfo->ii_UniqueStrats;
678 * If any of the input values are NULL, the constraint check is assumed to
679 * pass (i.e., we assume the operators are strict).
681 for (i = 0; i < index_natts; i++)
688 * Search the tuples that are in the index for any violations, including
689 * tuples that aren't visible yet.
691 InitDirtySnapshot(DirtySnapshot);
693 for (i = 0; i < index_natts; i++)
695 ScanKeyEntryInitialize(&scankeys[i],
706 * Need a TupleTableSlot to put existing tuples in.
708 * To use FormIndexDatum, we have to make the econtext's scantuple point
709 * to this slot. Be sure to save and restore caller's value for
712 existing_slot = MakeSingleTupleTableSlot(RelationGetDescr(heap));
714 econtext = GetPerTupleExprContext(estate);
715 save_scantuple = econtext->ecxt_scantuple;
716 econtext->ecxt_scantuple = existing_slot;
719 * May have to restart scan from this point if a potential conflict is
725 index_scan = index_beginscan(heap, index, &DirtySnapshot, index_natts, 0);
726 index_rescan(index_scan, scankeys, index_natts, NULL, 0);
728 while ((tup = index_getnext(index_scan,
729 ForwardScanDirection)) != NULL)
732 ItemPointerData ctid_wait;
733 XLTW_Oper reason_wait;
734 Datum existing_values[INDEX_MAX_KEYS];
735 bool existing_isnull[INDEX_MAX_KEYS];
737 char *error_existing;
740 * Ignore the entry for the tuple we're trying to check.
742 if (ItemPointerIsValid(tupleid) &&
743 ItemPointerEquals(tupleid, &tup->t_self))
745 if (found_self) /* should not happen */
746 elog(ERROR, "found self tuple multiple times in index \"%s\"",
747 RelationGetRelationName(index));
753 * Extract the index column values and isnull flags from the existing
756 ExecStoreTuple(tup, existing_slot, InvalidBuffer, false);
757 FormIndexDatum(indexInfo, existing_slot, estate,
758 existing_values, existing_isnull);
760 /* If lossy indexscan, must recheck the condition */
761 if (index_scan->xs_recheck)
763 if (!index_recheck_constraint(index,
768 continue; /* tuple doesn't actually match, so no
773 * At this point we have either a conflict or a potential conflict.
775 * If an in-progress transaction is affecting the visibility of this
776 * tuple, we need to wait for it to complete and then recheck (unless
777 * the caller requested not to). For simplicity we do rechecking by
778 * just restarting the whole scan --- this case probably doesn't
779 * happen often enough to be worth trying harder, and anyway we don't
780 * want to hold any index internal locks while waiting.
782 xwait = TransactionIdIsValid(DirtySnapshot.xmin) ?
783 DirtySnapshot.xmin : DirtySnapshot.xmax;
785 if (TransactionIdIsValid(xwait) &&
786 (waitMode == CEOUC_WAIT ||
787 (waitMode == CEOUC_LIVELOCK_PREVENTING_WAIT &&
788 DirtySnapshot.speculativeToken &&
789 TransactionIdPrecedes(GetCurrentTransactionId(), xwait))))
791 ctid_wait = tup->t_data->t_ctid;
792 reason_wait = indexInfo->ii_ExclusionOps ?
793 XLTW_RecheckExclusionConstr : XLTW_InsertIndex;
794 index_endscan(index_scan);
795 if (DirtySnapshot.speculativeToken)
796 SpeculativeInsertionWait(DirtySnapshot.xmin,
797 DirtySnapshot.speculativeToken);
799 XactLockTableWait(xwait, heap, &ctid_wait, reason_wait);
804 * We have a definite conflict (or a potential one, but the caller
805 * didn't want to wait). Return it to caller, or report it.
811 *conflictTid = tup->t_self;
815 error_new = BuildIndexValueDescription(index, values, isnull);
816 error_existing = BuildIndexValueDescription(index, existing_values,
820 (errcode(ERRCODE_EXCLUSION_VIOLATION),
821 errmsg("could not create exclusion constraint \"%s\"",
822 RelationGetRelationName(index)),
823 error_new && error_existing ?
824 errdetail("Key %s conflicts with key %s.",
825 error_new, error_existing) :
826 errdetail("Key conflicts exist."),
827 errtableconstraint(heap,
828 RelationGetRelationName(index))));
831 (errcode(ERRCODE_EXCLUSION_VIOLATION),
832 errmsg("conflicting key value violates exclusion constraint \"%s\"",
833 RelationGetRelationName(index)),
834 error_new && error_existing ?
835 errdetail("Key %s conflicts with existing key %s.",
836 error_new, error_existing) :
837 errdetail("Key conflicts with existing key."),
838 errtableconstraint(heap,
839 RelationGetRelationName(index))));
842 index_endscan(index_scan);
845 * Ordinarily, at this point the search should have found the originally
846 * inserted tuple (if any), unless we exited the loop early because of
847 * conflict. However, it is possible to define exclusion constraints for
848 * which that wouldn't be true --- for instance, if the operator is <>. So
849 * we no longer complain if found_self is still false.
852 econtext->ecxt_scantuple = save_scantuple;
854 ExecDropSingleTupleTableSlot(existing_slot);
860 * Check for violation of an exclusion constraint
862 * This is a dumbed down version of check_exclusion_or_unique_constraint
863 * for external callers. They don't need all the special modes.
866 check_exclusion_constraint(Relation heap, Relation index,
867 IndexInfo *indexInfo,
869 Datum *values, bool *isnull,
870 EState *estate, bool newIndex)
872 (void) check_exclusion_or_unique_constraint(heap, index, indexInfo, tupleid,
875 CEOUC_WAIT, false, NULL);
879 * Check existing tuple's index values to see if it really matches the
880 * exclusion condition against the new_values. Returns true if conflict.
883 index_recheck_constraint(Relation index, Oid *constr_procs,
884 Datum *existing_values, bool *existing_isnull,
887 int index_natts = index->rd_index->indnatts;
890 for (i = 0; i < index_natts; i++)
892 /* Assume the exclusion operators are strict */
893 if (existing_isnull[i])
896 if (!DatumGetBool(OidFunctionCall2Coll(constr_procs[i],
897 index->rd_indcollation[i],