Re: pgsql: Avoid coercing a whole-row variable that is already coerced

diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index 9290c7f..1601a97 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -1224,7 +1224,6 @@ typedef struct
 	/* Target type when converting whole-row vars */
 	Oid			to_rowtype;
 	bool	   *found_whole_row;	/* output flag */
-	bool		coerced_var;	/* var is under ConvertRowTypeExpr */
 } map_variable_attnos_context;
 
 static Node *
@@ -1268,29 +1267,22 @@ map_variable_attnos_mutator(Node *node,
 					/* Don't convert unless necessary. */
 					if (context->to_rowtype != var->vartype)
 					{
+						ConvertRowtypeExpr *r;
+
 						/* Var itself is converted to the requested type. */
 						newvar->vartype = context->to_rowtype;
 
 						/*
-						 * If this var is already under a ConvertRowtypeExpr,
-						 * we don't have to add another one.
+						 * And a conversion node on top to convert back to the
+						 * original type.
 						 */
-						if (!context->coerced_var)
-						{
-							ConvertRowtypeExpr *r;
-
-							/*
-							 * And a conversion node on top to convert back to
-							 * the original type.
-							 */
-							r = makeNode(ConvertRowtypeExpr);
-							r->arg = (Expr *) newvar;
-							r->resulttype = var->vartype;
-							r->convertformat = COERCE_IMPLICIT_CAST;
-							r->location = -1;
-
-							return (Node *) r;
-						}
+						r = makeNode(ConvertRowtypeExpr);
+						r->arg = (Expr *) newvar;
+						r->resulttype = var->vartype;
+						r->convertformat = COERCE_IMPLICIT_CAST;
+						r->location = -1;
+
+						return (Node *) r;
 					}
 				}
 			}
@@ -1306,15 +1298,20 @@ map_variable_attnos_mutator(Node *node,
 		 * If this is coercing a var (which is typical), convert only the var,
 		 * as against adding another ConvertRowtypeExpr over it.
 		 */
-		if (IsA(r->arg, Var))
+		if (IsA(r->arg, Var) && ((Var *)r->arg)->varattno == 0)
 		{
 			ConvertRowtypeExpr *newnode;
+			Var		   *var = (Var *) r->arg;
+			Var		   *newvar = (Var *) palloc(sizeof(Var));
+
+			*newvar = *var;
+			/* Var itself is converted to the requested type. */
+			if (OidIsValid(context->to_rowtype))
+				newvar->vartype = context->to_rowtype;
 
 			newnode = (ConvertRowtypeExpr *) palloc(sizeof(ConvertRowtypeExpr));
 			*newnode = *r;
-			context->coerced_var = true;
-			newnode->arg = (Expr *) map_variable_attnos_mutator((Node *) r->arg, context);
-			context->coerced_var = false;
+			newnode->arg = (Expr *) newvar;
 
 			return (Node *) newnode;
 		}
@@ -1351,7 +1348,6 @@ map_variable_attnos(Node *node,
 	context.map_length = map_length;
 	context.to_rowtype = to_rowtype;
 	context.found_whole_row = found_whole_row;
-	context.coerced_var = false;
 
 	*found_whole_row = false;