Fix replica identity check for INSERT ON CONFLICT DO UPDATE.

If an INSERT has an ON CONFLICT DO UPDATE clause, the executor must
check that the target relation supports UPDATE as well as INSERT. In
particular, it must check that the target relation has a REPLICA
IDENTITY if it publishes updates. Formerly, it was not doing this
check, which could lead to silently breaking replication.

Fix by adding such a check to CheckValidResultRel(), which requires
adding a new onConflictAction argument. In back-branches, preserve ABI
compatibility by introducing a wrapper function with the original
signature.

Author: Zhijie Hou <houzj.fnst@fujitsu.com>
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com>
Tested-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/OS3PR01MB57180C87E43A679A730482DF94B62@OS3PR01MB5718.jpnprd01.prod.outlook.com
Backpatch-through: 13

src/backend/commands/copyfrom.c

@@ -919,7 +919,7 @@ CopyFrom(CopyFromState cstate)
 	ExecInitResultRelation(estate, resultRelInfo, 1);
 
 	/* Verify the named relation is a valid target for INSERT */
-	CheckValidResultRel(resultRelInfo, CMD_INSERT, NIL);
+	CheckValidResultRel(resultRelInfo, CMD_INSERT, ONCONFLICT_NONE, NIL);
 
 	ExecOpenIndices(resultRelInfo, false);
 

src/backend/executor/execMain.c

@@ -1036,6 +1036,9 @@ 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.
+ *
  * For MERGE, mergeActions is the list of actions that may be performed.  The
  * result relation is required to support every action, regardless of whether
  * or not they are all executed.
@@ -1045,7 +1048,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
  */
 void
 CheckValidResultRel(ResultRelInfo *resultRelInfo, CmdType operation,
-					List *mergeActions)
+					OnConflictAction onConflictAction, List *mergeActions)
 {
 	Relation	resultRel = resultRelInfo->ri_RelationDesc;
 	FdwRoutine *fdwroutine;
@@ -1059,6 +1062,13 @@ 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,

src/backend/executor/execPartition.c

@@ -360,8 +360,12 @@ ExecFindPartition(ModifyTableState *mtstate,
 											   true, false);
 				if (rri)
 				{
+					ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
+
 					/* Verify this ResultRelInfo allows INSERTs */
-					CheckValidResultRel(rri, CMD_INSERT, NIL);
+					CheckValidResultRel(rri, CMD_INSERT,
+										node ? node->onConflictAction : ONCONFLICT_NONE,
+										NIL);
 
 					/*
 					 * Initialize information needed to insert this and
@@ -527,7 +531,8 @@ 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, NIL);
+	CheckValidResultRel(leaf_part_rri, CMD_INSERT,
+						node ? node->onConflictAction : ONCONFLICT_NONE, NIL);
 
 	/*
 	 * Open partition indices.  The user may have asked to check for conflicts

src/backend/executor/nodeModifyTable.c

@@ -4811,7 +4811,8 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		/*
 		 * Verify result relation is a valid target for the current operation
 		 */
-		CheckValidResultRel(resultRelInfo, operation, mergeActions);
+		CheckValidResultRel(resultRelInfo, operation, node->onConflictAction,
+							mergeActions);
 
 		resultRelInfo++;
 		i++;