Fix interaction of foreign tuple routing with remote triggers.

Without these fixes, changes to the inserted tuple made by remote
triggers are ignored when building local RETURNING tuples.

In the core code, call ExecInitRoutingInfo at a later point from
within ExecInitPartitionInfo so that the FDW callback gets invoked
after the returning list has been built.  But move CheckValidResultRel
out of ExecInitRoutingInfo so that it can happen at an earlier stage.

In postgres_fdw, refactor assorted deparsing functions to work with
the RTE rather than the PlannerInfo, which saves us having to
construct a fake PlannerInfo in cases where we don't have a real one.
Then, we can pass down a constructed RTE that yields the correct
deparse result when no real one exists.  Unfortunately, this
necessitates a hack that understands how the core code manages RT
indexes for update tuple routing, which is ugly, but we don't have a
better idea right now.

Original report, analysis, and patch by Etsuro Fujita.  Heavily
refactored by me.  Then worked over some more by Amit Langote.

Discussion: http://postgr.es/m/5AD4882B.10002@lab.ntt.co.jp

contrib/postgres_fdw/deparse.c

@@ -125,7 +125,7 @@ static char *deparse_type_name(Oid type_oid, int32 typemod);
  * Functions to construct string representation of a node tree.
  */
 static void deparseTargetList(StringInfo buf,
-				  PlannerInfo *root,
+				  RangeTblEntry *rte,
 				  Index rtindex,
 				  Relation rel,
 				  bool is_returning,
@@ -137,13 +137,13 @@ static void deparseExplicitTargetList(List *tlist,
 						  List **retrieved_attrs,
 						  deparse_expr_cxt *context);
 static void deparseSubqueryTargetList(deparse_expr_cxt *context);
-static void deparseReturningList(StringInfo buf, PlannerInfo *root,
+static void deparseReturningList(StringInfo buf, RangeTblEntry *rte,
 					 Index rtindex, Relation rel,
 					 bool trig_after_row,
 					 List *returningList,
 					 List **retrieved_attrs);
 static void deparseColumnRef(StringInfo buf, int varno, int varattno,
-				 PlannerInfo *root, bool qualify_col);
+				 RangeTblEntry *rte, bool qualify_col);
 static void deparseRelation(StringInfo buf, Relation rel);
 static void deparseExpr(Expr *expr, deparse_expr_cxt *context);
 static void deparseVar(Var *node, deparse_expr_cxt *context);
@@ -1050,7 +1050,7 @@ deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs,
 		 */
 		Relation	rel = heap_open(rte->relid, NoLock);
 
-		deparseTargetList(buf, root, foreignrel->relid, rel, false,
+		deparseTargetList(buf, rte, foreignrel->relid, rel, false,
 						  fpinfo->attrs_used, false, retrieved_attrs);
 		heap_close(rel, NoLock);
 	}
@@ -1099,7 +1099,7 @@ deparseFromExpr(List *quals, deparse_expr_cxt *context)
  */
 static void
 deparseTargetList(StringInfo buf,
-				  PlannerInfo *root,
+				  RangeTblEntry *rte,
 				  Index rtindex,
 				  Relation rel,
 				  bool is_returning,
@@ -1137,7 +1137,7 @@ deparseTargetList(StringInfo buf,
 				appendStringInfoString(buf, " RETURNING ");
 			first = false;
 
-			deparseColumnRef(buf, rtindex, i, root, qualify_col);
+			deparseColumnRef(buf, rtindex, i, rte, qualify_col);
 
 			*retrieved_attrs = lappend_int(*retrieved_attrs, i);
 		}
@@ -1649,7 +1649,7 @@ deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
  * to *retrieved_attrs.
  */
 void
-deparseInsertSql(StringInfo buf, PlannerInfo *root,
+deparseInsertSql(StringInfo buf, RangeTblEntry *rte,
 				 Index rtindex, Relation rel,
 				 List *targetAttrs, bool doNothing,
 				 List *returningList, List **retrieved_attrs)
@@ -1674,7 +1674,7 @@ deparseInsertSql(StringInfo buf, PlannerInfo *root,
 				appendStringInfoString(buf, ", ");
 			first = false;
 
-			deparseColumnRef(buf, rtindex, attnum, root, false);
+			deparseColumnRef(buf, rtindex, attnum, rte, false);
 		}
 
 		appendStringInfoString(buf, ") VALUES (");
@@ -1699,7 +1699,7 @@ deparseInsertSql(StringInfo buf, PlannerInfo *root,
 	if (doNothing)
 		appendStringInfoString(buf, " ON CONFLICT DO NOTHING");
 
-	deparseReturningList(buf, root, rtindex, rel,
+	deparseReturningList(buf, rte, rtindex, rel,
 						 rel->trigdesc && rel->trigdesc->trig_insert_after_row,
 						 returningList, retrieved_attrs);
 }
@@ -1712,7 +1712,7 @@ deparseInsertSql(StringInfo buf, PlannerInfo *root,
  * to *retrieved_attrs.
  */
 void
-deparseUpdateSql(StringInfo buf, PlannerInfo *root,
+deparseUpdateSql(StringInfo buf, RangeTblEntry *rte,
 				 Index rtindex, Relation rel,
 				 List *targetAttrs, List *returningList,
 				 List **retrieved_attrs)
@@ -1735,13 +1735,13 @@ deparseUpdateSql(StringInfo buf, PlannerInfo *root,
 			appendStringInfoString(buf, ", ");
 		first = false;
 
-		deparseColumnRef(buf, rtindex, attnum, root, false);
+		deparseColumnRef(buf, rtindex, attnum, rte, false);
 		appendStringInfo(buf, " = $%d", pindex);
 		pindex++;
 	}
 	appendStringInfoString(buf, " WHERE ctid = $1");
 
-	deparseReturningList(buf, root, rtindex, rel,
+	deparseReturningList(buf, rte, rtindex, rel,
 						 rel->trigdesc && rel->trigdesc->trig_update_after_row,
 						 returningList, retrieved_attrs);
 }
@@ -1777,6 +1777,7 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
 	int			nestlevel;
 	bool		first;
 	ListCell   *lc;
+	RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
 
 	/* Set up context struct for recursion */
 	context.root = root;
@@ -1808,7 +1809,7 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
 			appendStringInfoString(buf, ", ");
 		first = false;
 
-		deparseColumnRef(buf, rtindex, attnum, root, false);
+		deparseColumnRef(buf, rtindex, attnum, rte, false);
 		appendStringInfoString(buf, " = ");
 		deparseExpr((Expr *) tle->expr, &context);
 	}
@@ -1835,7 +1836,7 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
 		deparseExplicitTargetList(returningList, true, retrieved_attrs,
 								  &context);
 	else
-		deparseReturningList(buf, root, rtindex, rel, false,
+		deparseReturningList(buf, rte, rtindex, rel, false,
 							 returningList, retrieved_attrs);
 }
 
@@ -1847,7 +1848,7 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
  * to *retrieved_attrs.
  */
 void
-deparseDeleteSql(StringInfo buf, PlannerInfo *root,
+deparseDeleteSql(StringInfo buf, RangeTblEntry *rte,
 				 Index rtindex, Relation rel,
 				 List *returningList,
 				 List **retrieved_attrs)
@@ -1856,7 +1857,7 @@ deparseDeleteSql(StringInfo buf, PlannerInfo *root,
 	deparseRelation(buf, rel);
 	appendStringInfoString(buf, " WHERE ctid = $1");
 
-	deparseReturningList(buf, root, rtindex, rel,
+	deparseReturningList(buf, rte, rtindex, rel,
 						 rel->trigdesc && rel->trigdesc->trig_delete_after_row,
 						 returningList, retrieved_attrs);
 }
@@ -1918,7 +1919,8 @@ deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
 		deparseExplicitTargetList(returningList, true, retrieved_attrs,
 								  &context);
 	else
-		deparseReturningList(buf, root, rtindex, rel, false,
+		deparseReturningList(buf, planner_rt_fetch(rtindex, root),
+							 rtindex, rel, false,
 							 returningList, retrieved_attrs);
 }
 
@@ -1926,7 +1928,7 @@ deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
  * Add a RETURNING clause, if needed, to an INSERT/UPDATE/DELETE.
  */
 static void
-deparseReturningList(StringInfo buf, PlannerInfo *root,
+deparseReturningList(StringInfo buf, RangeTblEntry *rte,
 					 Index rtindex, Relation rel,
 					 bool trig_after_row,
 					 List *returningList,
@@ -1952,7 +1954,7 @@ deparseReturningList(StringInfo buf, PlannerInfo *root,
 	}
 
 	if (attrs_used != NULL)
-		deparseTargetList(buf, root, rtindex, rel, true, attrs_used, false,
+		deparseTargetList(buf, rte, rtindex, rel, true, attrs_used, false,
 						  retrieved_attrs);
 	else
 		*retrieved_attrs = NIL;
@@ -2048,11 +2050,9 @@ deparseAnalyzeSql(StringInfo buf, Relation rel, List **retrieved_attrs)
  * If qualify_col is true, qualify column name with the alias of relation.
  */
 static void
-deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
+deparseColumnRef(StringInfo buf, int varno, int varattno, RangeTblEntry *rte,
 				 bool qualify_col)
 {
-	RangeTblEntry *rte;
-
 	/* We support fetching the remote side's CTID and OID. */
 	if (varattno == SelfItemPointerAttributeNumber)
 	{
@@ -2077,10 +2077,7 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
 		Oid			fetchval = 0;
 
 		if (varattno == TableOidAttributeNumber)
-		{
-			rte = planner_rt_fetch(varno, root);
 			fetchval = rte->relid;
-		}
 
 		if (qualify_col)
 		{
@@ -2100,9 +2097,6 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
 		/* Required only to be passed down to deparseTargetList(). */
 		List	   *retrieved_attrs;
 
-		/* Get RangeTblEntry from array in PlannerInfo. */
-		rte = planner_rt_fetch(varno, root);
-
 		/*
 		 * The lock on the relation will be held by upper callers, so it's
 		 * fine to open it with no lock here.
@@ -2134,7 +2128,7 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
 		}
 
 		appendStringInfoString(buf, "ROW(");
-		deparseTargetList(buf, root, varno, rel, false, attrs_used, qualify_col,
+		deparseTargetList(buf, rte, varno, rel, false, attrs_used, qualify_col,
 						  &retrieved_attrs);
 		appendStringInfoChar(buf, ')');
 
@@ -2154,9 +2148,6 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
 		/* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */
 		Assert(!IS_SPECIAL_VARNO(varno));
 
-		/* Get RangeTblEntry from array in PlannerInfo. */
-		rte = planner_rt_fetch(varno, root);
-
 		/*
 		 * If it's a column of a foreign table, and it has the column_name FDW
 		 * option, use that value.
@@ -2354,7 +2345,8 @@ deparseVar(Var *node, deparse_expr_cxt *context)
 
 	if (bms_is_member(node->varno, relids) && node->varlevelsup == 0)
 		deparseColumnRef(context->buf, node->varno, node->varattno,
-						 context->root, qualify_col);
+						 planner_rt_fetch(node->varno, context->root),
+						 qualify_col);
 	else
 	{
 		/* Treat like a Param */

contrib/postgres_fdw/expected/postgres_fdw.out

@@ -7454,6 +7454,48 @@ select tableoid::regclass, * FROM itrtest;
  remp1    | 1 | foo
 (1 row)
 
+delete from itrtest;
+drop index loct1_idx;
+-- Test that remote triggers work with insert tuple routing
+create function br_insert_trigfunc() returns trigger as $$
+begin
+	new.b := new.b || ' triggered !';
+	return new;
+end
+$$ language plpgsql;
+create trigger loct1_br_insert_trigger before insert on loct1
+	for each row execute procedure br_insert_trigfunc();
+create trigger loct2_br_insert_trigger before insert on loct2
+	for each row execute procedure br_insert_trigfunc();
+-- The new values are concatenated with ' triggered !'
+insert into itrtest values (1, 'foo') returning *;
+ a |        b        
+---+-----------------
+ 1 | foo triggered !
+(1 row)
+
+insert into itrtest values (2, 'qux') returning *;
+ a |        b        
+---+-----------------
+ 2 | qux triggered !
+(1 row)
+
+insert into itrtest values (1, 'test1'), (2, 'test2') returning *;
+ a |         b         
+---+-------------------
+ 1 | test1 triggered !
+ 2 | test2 triggered !
+(2 rows)
+
+with result as (insert into itrtest values (1, 'test1'), (2, 'test2') returning *) select * from result;
+ a |         b         
+---+-------------------
+ 1 | test1 triggered !
+ 2 | test2 triggered !
+(2 rows)
+
+drop trigger loct1_br_insert_trigger on loct1;
+drop trigger loct2_br_insert_trigger on loct2;
 drop table itrtest;
 drop table loct1;
 drop table loct2;
@@ -7518,6 +7560,57 @@ select tableoid::regclass, * FROM locp;
 
 -- The executor should not let unexercised FDWs shut down
 update utrtest set a = 1 where b = 'foo';
+-- Test that remote triggers work with update tuple routing
+create trigger loct_br_insert_trigger before insert on loct
+	for each row execute procedure br_insert_trigfunc();
+delete from utrtest;
+insert into utrtest values (2, 'qux');
+-- Check case where the foreign partition is a subplan target rel
+explain (verbose, costs off)
+update utrtest set a = 1 where a = 1 or a = 2 returning *;
+                                          QUERY PLAN                                          
+----------------------------------------------------------------------------------------------
+ Update on public.utrtest
+   Output: remp.a, remp.b
+   Foreign Update on public.remp
+   Update on public.locp
+   ->  Foreign Update on public.remp
+         Remote SQL: UPDATE public.loct SET a = 1 WHERE (((a = 1) OR (a = 2))) RETURNING a, b
+   ->  Seq Scan on public.locp
+         Output: 1, locp.b, locp.ctid
+         Filter: ((locp.a = 1) OR (locp.a = 2))
+(9 rows)
+
+-- The new values are concatenated with ' triggered !'
+update utrtest set a = 1 where a = 1 or a = 2 returning *;
+ a |        b        
+---+-----------------
+ 1 | qux triggered !
+(1 row)
+
+delete from utrtest;
+insert into utrtest values (2, 'qux');
+-- Check case where the foreign partition isn't a subplan target rel
+explain (verbose, costs off)
+update utrtest set a = 1 where a = 2 returning *;
+              QUERY PLAN              
+--------------------------------------
+ Update on public.utrtest
+   Output: locp.a, locp.b
+   Update on public.locp
+   ->  Seq Scan on public.locp
+         Output: 1, locp.b, locp.ctid
+         Filter: (locp.a = 2)
+(6 rows)
+
+-- The new values are concatenated with ' triggered !'
+update utrtest set a = 1 where a = 2 returning *;
+ a |        b        
+---+-----------------
+ 1 | qux triggered !
+(1 row)
+
+drop trigger loct_br_insert_trigger on loct;
 drop table utrtest;
 drop table loct;
 -- Test copy tuple routing

contrib/postgres_fdw/postgres_fdw.c

@@ -381,6 +381,7 @@ static void create_cursor(ForeignScanState *node);
 static void fetch_more_data(ForeignScanState *node);
 static void close_cursor(PGconn *conn, unsigned int cursor_number);
 static PgFdwModifyState *create_foreign_modify(EState *estate,
+					  RangeTblEntry *rte,
 					  ResultRelInfo *resultRelInfo,
 					  CmdType operation,
 					  Plan *subplan,
@@ -1653,17 +1654,17 @@ postgresPlanForeignModify(PlannerInfo *root,
 	switch (operation)
 	{
 		case CMD_INSERT:
-			deparseInsertSql(&sql, root, resultRelation, rel,
+			deparseInsertSql(&sql, rte, resultRelation, rel,
 							 targetAttrs, doNothing, returningList,
 							 &retrieved_attrs);
 			break;
 		case CMD_UPDATE:
-			deparseUpdateSql(&sql, root, resultRelation, rel,
+			deparseUpdateSql(&sql, rte, resultRelation, rel,
 							 targetAttrs, returningList,
 							 &retrieved_attrs);
 			break;
 		case CMD_DELETE:
-			deparseDeleteSql(&sql, root, resultRelation, rel,
+			deparseDeleteSql(&sql, rte, resultRelation, rel,
 							 returningList,
 							 &retrieved_attrs);
 			break;
@@ -1700,6 +1701,7 @@ postgresBeginForeignModify(ModifyTableState *mtstate,
 	List	   *target_attrs;
 	bool		has_returning;
 	List	   *retrieved_attrs;
+	RangeTblEntry *rte;
 
 	/*
 	 * Do nothing in EXPLAIN (no ANALYZE) case.  resultRelInfo->ri_FdwState
@@ -1718,8 +1720,13 @@ postgresBeginForeignModify(ModifyTableState *mtstate,
 	retrieved_attrs = (List *) list_nth(fdw_private,
 										FdwModifyPrivateRetrievedAttrs);
 
+	/* Find RTE. */
+	rte = rt_fetch(resultRelInfo->ri_RangeTableIndex,
+				   mtstate->ps.state->es_range_table);
+
 	/* Construct an execution state. */
 	fmstate = create_foreign_modify(mtstate->ps.state,
+									rte,
 									resultRelInfo,
 									mtstate->operation,
 									mtstate->mt_plans[subplan_index]->plan,
@@ -1974,11 +1981,11 @@ postgresBeginForeignInsert(ModifyTableState *mtstate,
 						   ResultRelInfo *resultRelInfo)
 {
 	PgFdwModifyState *fmstate;
-	Plan	   *plan = mtstate->ps.plan;
+	ModifyTable *plan = castNode(ModifyTable, mtstate->ps.plan);
+	EState	   *estate = mtstate->ps.state;
+	Index		resultRelation = resultRelInfo->ri_RangeTableIndex;
 	Relation	rel = resultRelInfo->ri_RelationDesc;
 	RangeTblEntry *rte;
-	Query	   *query;
-	PlannerInfo *root;
 	TupleDesc	tupdesc = RelationGetDescr(rel);
 	int			attnum;
 	StringInfoData sql;
@@ -1988,18 +1995,6 @@ postgresBeginForeignInsert(ModifyTableState *mtstate,
 
 	initStringInfo(&sql);
 
-	/* Set up largely-dummy planner state. */
-	rte = makeNode(RangeTblEntry);
-	rte->rtekind = RTE_RELATION;
-	rte->relid = RelationGetRelid(rel);
-	rte->relkind = RELKIND_FOREIGN_TABLE;
-	query = makeNode(Query);
-	query->commandType = CMD_INSERT;
-	query->resultRelation = 1;
-	query->rtable = list_make1(rte);
-	root = makeNode(PlannerInfo);
-	root->parse = query;
-
 	/* We transmit all columns that are defined in the foreign table. */
 	for (attnum = 1; attnum <= tupdesc->natts; attnum++)
 	{
@@ -2022,12 +2017,41 @@ postgresBeginForeignInsert(ModifyTableState *mtstate,
 				 (int) onConflictAction);
 	}
 
+	/*
+	 * If the foreign table is a partition, we need to create a new RTE
+	 * describing the foreign table for use by deparseInsertSql and
+	 * create_foreign_modify() below, after first copying the parent's
+	 * RTE and modifying some fields to describe the foreign partition to
+	 * work on. However, if this is invoked by UPDATE, the existing RTE
+	 * may already correspond to this partition if it is one of the
+	 * UPDATE subplan target rels; in that case, we can just use the
+	 * existing RTE as-is.
+	 */
+	rte = list_nth(estate->es_range_table, resultRelation - 1);
+	if (rte->relid != RelationGetRelid(rel))
+	{
+		rte = copyObject(rte);
+		rte->relid = RelationGetRelid(rel);
+		rte->relkind = RELKIND_FOREIGN_TABLE;
+
+		/*
+		 * For UPDATE, we must use the RT index of the first subplan
+		 * target rel's RTE, because the core code would have built
+		 * expressions for the partition, such as RETURNING, using that
+		 * RT index as varno of Vars contained in those expressions.
+		 */
+		if (plan && plan->operation == CMD_UPDATE &&
+			resultRelation == plan->nominalRelation)
+			resultRelation = mtstate->resultRelInfo[0].ri_RangeTableIndex;
+	}
+
 	/* Construct the SQL command string. */
-	deparseInsertSql(&sql, root, 1, rel, targetAttrs, doNothing,
+	deparseInsertSql(&sql, rte, resultRelation, rel, targetAttrs, doNothing,
 					 resultRelInfo->ri_returningList, &retrieved_attrs);
 
 	/* Construct an execution state. */
 	fmstate = create_foreign_modify(mtstate->ps.state,
+									rte,
 									resultRelInfo,
 									CMD_INSERT,
 									NULL,
@@ -3255,6 +3279,7 @@ close_cursor(PGconn *conn, unsigned int cursor_number)
  */
 static PgFdwModifyState *
 create_foreign_modify(EState *estate,
+					  RangeTblEntry *rte,
 					  ResultRelInfo *resultRelInfo,
 					  CmdType operation,
 					  Plan *subplan,
@@ -3266,7 +3291,6 @@ create_foreign_modify(EState *estate,
 	PgFdwModifyState *fmstate;
 	Relation	rel = resultRelInfo->ri_RelationDesc;
 	TupleDesc	tupdesc = RelationGetDescr(rel);
-	RangeTblEntry *rte;
 	Oid			userid;
 	ForeignTable *table;
 	UserMapping *user;
@@ -3283,7 +3307,6 @@ create_foreign_modify(EState *estate,
 	 * Identify which user to do the remote access as.  This should match what
 	 * ExecCheckRTEPerms() does.
 	 */
-	rte = rt_fetch(resultRelInfo->ri_RangeTableIndex, estate->es_range_table);
 	userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 
 	/* Get info about foreign table. */

contrib/postgres_fdw/postgres_fdw.h

@@ -140,11 +140,11 @@ extern void classifyConditions(PlannerInfo *root,
 extern bool is_foreign_expr(PlannerInfo *root,
 				RelOptInfo *baserel,
 				Expr *expr);
-extern void deparseInsertSql(StringInfo buf, PlannerInfo *root,
+extern void deparseInsertSql(StringInfo buf, RangeTblEntry *rte,
 				 Index rtindex, Relation rel,
 				 List *targetAttrs, bool doNothing, List *returningList,
 				 List **retrieved_attrs);
-extern void deparseUpdateSql(StringInfo buf, PlannerInfo *root,
+extern void deparseUpdateSql(StringInfo buf, RangeTblEntry *rte,
 				 Index rtindex, Relation rel,
 				 List *targetAttrs, List *returningList,
 				 List **retrieved_attrs);
@@ -157,7 +157,7 @@ extern void deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
 					   List **params_list,
 					   List *returningList,
 					   List **retrieved_attrs);
-extern void deparseDeleteSql(StringInfo buf, PlannerInfo *root,
+extern void deparseDeleteSql(StringInfo buf, RangeTblEntry *rte,
 				 Index rtindex, Relation rel,
 				 List *returningList,
 				 List **retrieved_attrs);

contrib/postgres_fdw/sql/postgres_fdw.sql

@@ -1804,6 +1804,31 @@ insert into itrtest values (1, 'bar') on conflict (a) do update set b = excluded
 
 select tableoid::regclass, * FROM itrtest;
 
+delete from itrtest;
+
+drop index loct1_idx;
+
+-- Test that remote triggers work with insert tuple routing
+create function br_insert_trigfunc() returns trigger as $$
+begin
+	new.b := new.b || ' triggered !';
+	return new;
+end
+$$ language plpgsql;
+create trigger loct1_br_insert_trigger before insert on loct1
+	for each row execute procedure br_insert_trigfunc();
+create trigger loct2_br_insert_trigger before insert on loct2
+	for each row execute procedure br_insert_trigfunc();
+
+-- The new values are concatenated with ' triggered !'
+insert into itrtest values (1, 'foo') returning *;
+insert into itrtest values (2, 'qux') returning *;
+insert into itrtest values (1, 'test1'), (2, 'test2') returning *;
+with result as (insert into itrtest values (1, 'test1'), (2, 'test2') returning *) select * from result;
+
+drop trigger loct1_br_insert_trigger on loct1;
+drop trigger loct2_br_insert_trigger on loct2;
+
 drop table itrtest;
 drop table loct1;
 drop table loct2;
@@ -1836,6 +1861,30 @@ select tableoid::regclass, * FROM locp;
 -- The executor should not let unexercised FDWs shut down
 update utrtest set a = 1 where b = 'foo';
 
+-- Test that remote triggers work with update tuple routing
+create trigger loct_br_insert_trigger before insert on loct
+	for each row execute procedure br_insert_trigfunc();
+
+delete from utrtest;
+insert into utrtest values (2, 'qux');
+
+-- Check case where the foreign partition is a subplan target rel
+explain (verbose, costs off)
+update utrtest set a = 1 where a = 1 or a = 2 returning *;
+-- The new values are concatenated with ' triggered !'
+update utrtest set a = 1 where a = 1 or a = 2 returning *;
+
+delete from utrtest;
+insert into utrtest values (2, 'qux');
+
+-- Check case where the foreign partition isn't a subplan target rel
+explain (verbose, costs off)
+update utrtest set a = 1 where a = 2 returning *;
+-- The new values are concatenated with ' triggered !'
+update utrtest set a = 1 where a = 2 returning *;
+
+drop trigger loct_br_insert_trigger on loct;
+
 drop table utrtest;
 drop table loct;
 

src/backend/executor/execPartition.c

@@ -332,6 +332,13 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 					  rootrel,
 					  estate->es_instrument);
 
+	/*
+	 * Verify result relation is a valid target for an INSERT.  An UPDATE of a
+	 * 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);
+
 	/*
 	 * Since we've just initialized this ResultRelInfo, it's not in any list
 	 * attached to the estate as yet.  Add it, so that it can be found later.
@@ -344,9 +351,6 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 		lappend(estate->es_tuple_routing_result_relations,
 				leaf_part_rri);
 
-	/* Set up information needed for routing tuples to this partition. */
-	ExecInitRoutingInfo(mtstate, estate, proute, leaf_part_rri, partidx);
-
 	/*
 	 * Open partition indices.  The user may have asked to check for conflicts
 	 * within this leaf partition and do "nothing" instead of throwing an
@@ -489,6 +493,9 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 									&mtstate->ps, RelationGetDescr(partrel));
 	}
 
+	/* Set up information needed for routing tuples to the partition. */
+	ExecInitRoutingInfo(mtstate, estate, proute, leaf_part_rri, partidx);
+
 	/*
 	 * If there is an ON CONFLICT clause, initialize state for it.
 	 */
@@ -655,8 +662,7 @@ ExecInitPartitionInfo(ModifyTableState *mtstate,
 
 /*
  * ExecInitRoutingInfo
- *		Set up information needed for routing tuples to a leaf partition if
- *		routable; else abort the operation
+ *		Set up information needed for routing tuples to a leaf partition
  */
 void
 ExecInitRoutingInfo(ModifyTableState *mtstate,
@@ -667,9 +673,6 @@ ExecInitRoutingInfo(ModifyTableState *mtstate,
 {
 	MemoryContext oldContext;
 
-	/* Verify the partition is a valid target for INSERT */
-	CheckValidResultRel(partRelInfo, CMD_INSERT);
-
 	/*
 	 * Switch into per-query memory context.
 	 */

src/backend/executor/nodeModifyTable.c

@@ -1700,20 +1700,24 @@ ExecPrepareTupleRouting(ModifyTableState *mtstate,
 										partidx);
 
 	/*
-	 * Set up information needed for routing tuples to the partition if we
-	 * didn't yet (ExecInitRoutingInfo would abort the operation if the
-	 * partition isn't routable).
+	 * Check whether the partition is routable if we didn't yet
 	 *
 	 * Note: an UPDATE of a partition key invokes an INSERT that moves the
-	 * tuple to a new partition.  This setup would be needed for a subplan
+	 * tuple to a new partition.  This check would be applied to a subplan
 	 * partition of such an UPDATE that is chosen as the partition to route
-	 * the tuple to.  The reason we do this setup here rather than in
+	 * the tuple to.  The reason we do this check here rather than in
 	 * ExecSetupPartitionTupleRouting is to avoid aborting such an UPDATE
 	 * unnecessarily due to non-routable subplan partitions that may not be
 	 * chosen for update tuple movement after all.
 	 */
 	if (!partrel->ri_PartitionReadyForRouting)
+	{
+		/* Verify the partition is a valid target for INSERT. */
+		CheckValidResultRel(partrel, CMD_INSERT);
+
+		/* Set up information needed for routing tuples to the partition. */
 		ExecInitRoutingInfo(mtstate, estate, proute, partrel, partidx);
+	}
 
 	/*
 	 * Make it look like we are inserting into the partition.