3 files changed, 30 insertions, 4 deletions

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index c3d497e3fa5..00bbcea2a5a 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -981,11 +981,15 @@ InitPlan(QueryDesc *queryDesc, int eflags)
  * Generally the parser and/or planner should have noticed any such mistake
  * already, but let's make sure.
  *
+ * For INSERT ON CONFLICT, the result relation is required to support the
+ * onConflictAction, regardless of whether a conflict actually occurs.
+ *
  * Note: when changing this function, you probably also need to look at
  * CheckValidRowMarkRel.
  */
 void
-CheckValidResultRel(ResultRelInfo *resultRelInfo, CmdType operation)
+CheckValidResultRelNew(ResultRelInfo *resultRelInfo, CmdType operation,
+					   OnConflictAction onConflictAction)
 {
 	Relation	resultRel = resultRelInfo->ri_RelationDesc;
 	TriggerDesc *trigDesc = resultRel->trigdesc;
@@ -1000,6 +1004,13 @@ CheckValidResultRel(ResultRelInfo *resultRelInfo, CmdType operation)
 		case RELKIND_RELATION:
 		case RELKIND_PARTITIONED_TABLE:
 			CheckCmdReplicaIdentity(resultRel, operation);
+
+			/*
+			 * For INSERT ON CONFLICT DO UPDATE, additionally check that the
+			 * target relation supports UPDATE.
+			 */
+			if (onConflictAction == ONCONFLICT_UPDATE)
+				CheckCmdReplicaIdentity(resultRel, CMD_UPDATE);
 			break;
 		case RELKIND_SEQUENCE:
 			ereport(ERROR,
@@ -1119,6 +1130,16 @@ CheckValidResultRel(ResultRelInfo *resultRelInfo, CmdType operation)
 }
 
 /*
+ * ABI-compatible wrapper to emulate old version of the above function.
+ * Do not call this version in new code.
+ */
+void
+CheckValidResultRel(ResultRelInfo *resultRelInfo, CmdType operation)
+{
+	return CheckValidResultRelNew(resultRelInfo, operation, ONCONFLICT_NONE);
+}
+
+/*
  * Check that a proposed rowmark target relation is a legal target
  *
  * In most cases parser and/or planner should have noticed this already, but
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 2fe21b7f2de..535ae2f09ff 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -360,8 +360,11 @@ ExecFindPartition(ModifyTableState *mtstate,
 											   true, false);
 				if (rri)
 				{
+					ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
+
 					/* Verify this ResultRelInfo allows INSERTs */
-					CheckValidResultRel(rri, CMD_INSERT);
+					CheckValidResultRelNew(rri, CMD_INSERT,
+										   node ? node->onConflictAction : ONCONFLICT_NONE);
 
 					/*
 					 * Initialize information needed to insert this and
@@ -527,7 +530,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 	 * partition-key becomes a DELETE+INSERT operation, so this check is still
 	 * required when the operation is CMD_UPDATE.
 	 */
-	CheckValidResultRel(leaf_part_rri, CMD_INSERT);
+	CheckValidResultRelNew(leaf_part_rri, CMD_INSERT,
+						   node ? node->onConflictAction : ONCONFLICT_NONE);
 
 	/*
 	 * Open partition indices.  The user may have asked to check for conflicts
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 1bd0ff60c12..fc10729a6ef 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -4241,7 +4241,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		/*
 		 * Verify result relation is a valid target for the current operation
 		 */
-		CheckValidResultRel(resultRelInfo, operation);
+		CheckValidResultRelNew(resultRelInfo, operation,
+							   node->onConflictAction);
 
 		resultRelInfo++;
 		i++;