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

Author: robertmhaas

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);
 }
@@ -1918,15 +1919,16 @@ 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);
 }
 
 /*
  * 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