Fix reporting of constraint violations for table partitioning.

After a tuple is routed to a partition, it has been converted from the
root table's row type to the partition's row type.  ExecConstraints
needs to report the failure using the original tuple and the parent's
tuple descriptor rather than the ones for the selected partition.

Amit Langote

src/backend/commands/copy.c

@@ -2426,6 +2426,7 @@ CopyFrom(CopyState cstate)
 					  cstate->rel,
 					  1,		/* dummy rangetable index */
 					  true,		/* do load partition check expression */
+					  NULL,
 					  0);
 
 	ExecOpenIndices(resultRelInfo, false);
@@ -2491,7 +2492,7 @@ CopyFrom(CopyState cstate)
 	for (;;)
 	{
 		TupleTableSlot *slot,
-					   *oldslot = NULL;
+					   *oldslot;
 		bool		skip_tuple;
 		Oid			loaded_oid = InvalidOid;
 
@@ -2533,6 +2534,7 @@ CopyFrom(CopyState cstate)
 		ExecStoreTuple(tuple, slot, InvalidBuffer, false);
 
 		/* Determine the partition to heap_insert the tuple into */
+		oldslot = slot;
 		if (cstate->partition_dispatch_info)
 		{
 			int			leaf_part_index;
@@ -2587,7 +2589,6 @@ CopyFrom(CopyState cstate)
 				 * point on.  Use a dedicated slot from this point on until
 				 * we're finished dealing with the partition.
 				 */
-				oldslot = slot;
 				slot = cstate->partition_tuple_slot;
 				Assert(slot != NULL);
 				ExecSetSlotDescriptor(slot, RelationGetDescr(partrel));
@@ -2624,7 +2625,7 @@ CopyFrom(CopyState cstate)
 				/* Check the constraints of the tuple */
 				if (cstate->rel->rd_att->constr ||
 					resultRelInfo->ri_PartitionCheck)
-					ExecConstraints(resultRelInfo, slot, estate);
+					ExecConstraints(resultRelInfo, slot, oldslot, estate);
 
 				if (useHeapMultiInsert)
 				{
@@ -2686,10 +2687,6 @@ CopyFrom(CopyState cstate)
 			{
 				resultRelInfo = saved_resultRelInfo;
 				estate->es_result_relation_info = resultRelInfo;
-
-				/* Switch back to the slot corresponding to the root table */
-				Assert(oldslot != NULL);
-				slot = oldslot;
 			}
 		}
 	}

src/backend/commands/tablecmds.c

@@ -1324,6 +1324,7 @@ ExecuteTruncate(TruncateStmt *stmt)
 						  rel,
 						  0,	/* dummy rangetable index */
 						  false,
+						  NULL,
 						  0);
 		resultRelInfo++;
 	}

src/backend/executor/execMain.c

@@ -828,6 +828,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 							  resultRelation,
 							  resultRelationIndex,
 							  true,
+							  NULL,
 							  estate->es_instrument);
 			resultRelInfo++;
 		}
@@ -1218,6 +1219,7 @@ InitResultRelInfo(ResultRelInfo *resultRelInfo,
 				  Relation resultRelationDesc,
 				  Index resultRelationIndex,
 				  bool load_partition_check,
+				  Relation partition_root,
 				  int instrument_options)
 {
 	MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
@@ -1259,6 +1261,11 @@ InitResultRelInfo(ResultRelInfo *resultRelInfo,
 		resultRelInfo->ri_PartitionCheck =
 							RelationGetPartitionQual(resultRelationDesc,
 													 true);
+	/*
+	 * The following gets set to NULL unless we are initializing leaf
+	 * partitions for tuple-routing.
+	 */
+	resultRelInfo->ri_PartitionRoot = partition_root;
 }
 
 /*
@@ -1322,6 +1329,7 @@ ExecGetTriggerResultRel(EState *estate, Oid relid)
 					  rel,
 					  0,		/* dummy rangetable index */
 					  true,
+					  NULL,
 					  estate->es_instrument);
 	estate->es_trig_target_relations =
 		lappend(estate->es_trig_target_relations, rInfo);
@@ -1743,9 +1751,21 @@ ExecPartitionCheck(ResultRelInfo *resultRelInfo, TupleTableSlot *slot,
 	return ExecQual(resultRelInfo->ri_PartitionCheckExpr, econtext, true);
 }
 
+/*
+ * ExecConstraints - check constraints of the tuple in 'slot'
+ *
+ * This checks the traditional NOT NULL and check constraints, as well as
+ * the partition constraint, if any.
+ *
+ * Note: 'slot' contains the tuple to check the constraints of, which may
+ * have been converted from the original input tuple after tuple routing,
+ * while 'orig_slot' contains the original tuple to be shown in the message,
+ * if an error occurs.
+ */
 void
 ExecConstraints(ResultRelInfo *resultRelInfo,
-				TupleTableSlot *slot, EState *estate)
+				TupleTableSlot *slot, TupleTableSlot *orig_slot,
+				EState *estate)
 {
 	Relation	rel = resultRelInfo->ri_RelationDesc;
 	TupleDesc	tupdesc = RelationGetDescr(rel);
@@ -1767,12 +1787,24 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
 				slot_attisnull(slot, attrChk))
 			{
 				char	   *val_desc;
+				Relation	orig_rel = rel;
+				TupleDesc	orig_tupdesc = tupdesc;
+
+				/*
+				 * choose the correct relation to build val_desc from the
+				 * tuple contained in orig_slot
+				 */
+				if (resultRelInfo->ri_PartitionRoot)
+				{
+					rel = resultRelInfo->ri_PartitionRoot;
+					tupdesc = RelationGetDescr(rel);
+				}
 
 				insertedCols = GetInsertedColumns(resultRelInfo, estate);
 				updatedCols = GetUpdatedColumns(resultRelInfo, estate);
 				modifiedCols = bms_union(insertedCols, updatedCols);
 				val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
-														 slot,
+														 orig_slot,
 														 tupdesc,
 														 modifiedCols,
 														 64);
@@ -1780,9 +1812,9 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
 				ereport(ERROR,
 						(errcode(ERRCODE_NOT_NULL_VIOLATION),
 						 errmsg("null value in column \"%s\" violates not-null constraint",
-							  NameStr(tupdesc->attrs[attrChk - 1]->attname)),
+						  NameStr(orig_tupdesc->attrs[attrChk - 1]->attname)),
 						 val_desc ? errdetail("Failing row contains %s.", val_desc) : 0,
-						 errtablecol(rel, attrChk)));
+						 errtablecol(orig_rel, attrChk)));
 			}
 		}
 	}
@@ -1794,21 +1826,29 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
 		if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
 		{
 			char	   *val_desc;
+			Relation	orig_rel = rel;
+
+			/* See the comment above. */
+			if (resultRelInfo->ri_PartitionRoot)
+			{
+				rel = resultRelInfo->ri_PartitionRoot;
+				tupdesc = RelationGetDescr(rel);
+			}
 
 			insertedCols = GetInsertedColumns(resultRelInfo, estate);
 			updatedCols = GetUpdatedColumns(resultRelInfo, estate);
 			modifiedCols = bms_union(insertedCols, updatedCols);
 			val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
-													 slot,
+													 orig_slot,
 													 tupdesc,
 													 modifiedCols,
 													 64);
 			ereport(ERROR,
 					(errcode(ERRCODE_CHECK_VIOLATION),
 					 errmsg("new row for relation \"%s\" violates check constraint \"%s\"",
-							RelationGetRelationName(rel), failed),
+							RelationGetRelationName(orig_rel), failed),
 			  val_desc ? errdetail("Failing row contains %s.", val_desc) : 0,
-					 errtableconstraint(rel, failed)));
+					 errtableconstraint(orig_rel, failed)));
 		}
 	}
 
@@ -1816,19 +1856,27 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
 		!ExecPartitionCheck(resultRelInfo, slot, estate))
 	{
 		char	   *val_desc;
+		Relation	orig_rel = rel;
+
+		/* See the comment above. */
+		if (resultRelInfo->ri_PartitionRoot)
+		{
+			rel = resultRelInfo->ri_PartitionRoot;
+			tupdesc = RelationGetDescr(rel);
+		}
 
 		insertedCols = GetInsertedColumns(resultRelInfo, estate);
 		updatedCols = GetUpdatedColumns(resultRelInfo, estate);
 		modifiedCols = bms_union(insertedCols, updatedCols);
 		val_desc = ExecBuildSlotValueDescription(RelationGetRelid(rel),
-												 slot,
+												 orig_slot,
 												 tupdesc,
 												 modifiedCols,
 												 64);
 		ereport(ERROR,
 				(errcode(ERRCODE_CHECK_VIOLATION),
 				 errmsg("new row for relation \"%s\" violates partition constraint",
-						RelationGetRelationName(rel)),
+						RelationGetRelationName(orig_rel)),
 		  val_desc ? errdetail("Failing row contains %s.", val_desc) : 0));
 	}
 }
@@ -3086,6 +3134,7 @@ ExecSetupPartitionTupleRouting(Relation rel,
 						  partrel,
 						  1,	 /* dummy */
 						  false,
+						  rel,
 						  0);
 
 		/*

src/backend/executor/nodeModifyTable.c

@@ -262,7 +262,7 @@ ExecInsert(ModifyTableState *mtstate,
 	Relation	resultRelationDesc;
 	Oid			newId;
 	List	   *recheckIndexes = NIL;
-	TupleTableSlot *oldslot = NULL;
+	TupleTableSlot *oldslot = slot;
 
 	/*
 	 * get the heap tuple out of the tuple table slot, making sure we have a
@@ -328,7 +328,6 @@ ExecInsert(ModifyTableState *mtstate,
 			 * point on, until we're finished dealing with the partition.
 			 * Use the dedicated slot for that.
 			 */
-			oldslot = slot;
 			slot = mtstate->mt_partition_tuple_slot;
 			Assert(slot != NULL);
 			ExecSetSlotDescriptor(slot, RelationGetDescr(partrel));
@@ -434,7 +433,7 @@ ExecInsert(ModifyTableState *mtstate,
 		 * Check the constraints of the tuple
 		 */
 		if (resultRelationDesc->rd_att->constr || resultRelInfo->ri_PartitionCheck)
-			ExecConstraints(resultRelInfo, slot, estate);
+			ExecConstraints(resultRelInfo, slot, oldslot, estate);
 
 		if (onconflict != ONCONFLICT_NONE && resultRelInfo->ri_NumIndices > 0)
 		{
@@ -579,10 +578,6 @@ ExecInsert(ModifyTableState *mtstate,
 	{
 		resultRelInfo = saved_resultRelInfo;
 		estate->es_result_relation_info = resultRelInfo;
-
-		/* Switch back to the slot corresponding to the root table */
-		Assert(oldslot != NULL);
-		slot = oldslot;
 	}
 
 	/*
@@ -994,10 +989,12 @@ lreplace:;
 								 resultRelInfo, slot, estate);
 
 		/*
-		 * Check the constraints of the tuple
+		 * Check the constraints of the tuple.  Note that we pass the same
+		 * slot for the orig_slot argument, because unlike ExecInsert(), no
+		 * tuple-routing is performed here, hence the slot remains unchanged.
 		 */
 		if (resultRelationDesc->rd_att->constr || resultRelInfo->ri_PartitionCheck)
-			ExecConstraints(resultRelInfo, slot, estate);
+			ExecConstraints(resultRelInfo, slot, slot, estate);
 
 		/*
 		 * replace the heap tuple

src/include/executor/executor.h

@@ -190,11 +190,13 @@ extern void InitResultRelInfo(ResultRelInfo *resultRelInfo,
 				  Relation resultRelationDesc,
 				  Index resultRelationIndex,
 				  bool load_partition_check,
+				  Relation partition_root,
 				  int instrument_options);
 extern ResultRelInfo *ExecGetTriggerResultRel(EState *estate, Oid relid);
 extern bool ExecContextForcesOids(PlanState *planstate, bool *hasoids);
 extern void ExecConstraints(ResultRelInfo *resultRelInfo,
-				TupleTableSlot *slot, EState *estate);
+				TupleTableSlot *slot, TupleTableSlot *orig_slot,
+				EState *estate);
 extern void ExecWithCheckOptions(WCOKind kind, ResultRelInfo *resultRelInfo,
 					 TupleTableSlot *slot, EState *estate);
 extern LockTupleMode ExecUpdateLockMode(EState *estate, ResultRelInfo *relinfo);

src/include/nodes/execnodes.h

@@ -349,6 +349,7 @@ typedef struct ResultRelInfo
 	List	   *ri_onConflictSetWhere;
 	List	   *ri_PartitionCheck;
 	List	   *ri_PartitionCheckExpr;
+	Relation	ri_PartitionRoot;
 } ResultRelInfo;
 
 /* ----------------

src/test/regress/expected/insert.out

@@ -333,5 +333,12 @@ select tableoid::regclass, * from p;
  p11      | 1 | 2
 (1 row)
 
+truncate p;
+alter table p add constraint check_b check (b = 3);
+-- check that correct input row is shown when constraint check_b fails on p11
+-- after "(1, 2)" is routed to it
+insert into p values (1, 2);
+ERROR:  new row for relation "p11" violates check constraint "check_b"
+DETAIL:  Failing row contains (1, 2).
 -- cleanup
 drop table p, p1, p11;

src/test/regress/sql/insert.sql

@@ -195,5 +195,11 @@ alter table p attach partition p1 for values from (1, 2) to (1, 10);
 insert into p values (1, 2);
 select tableoid::regclass, * from p;
 
+truncate p;
+alter table p add constraint check_b check (b = 3);
+-- check that correct input row is shown when constraint check_b fails on p11
+-- after "(1, 2)" is routed to it
+insert into p values (1, 2);
+
 -- cleanup
 drop table p, p1, p11;