3 files changed, 74 insertions, 0 deletions
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index d13cb582272..f489f140e37 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -26,6 +26,7 @@
 #include "postgres.h"
 
 #include "catalog/pg_type.h"
+#include "funcapi.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
@@ -1683,6 +1684,9 @@ pull_up_constant_function(PlannerInfo *root, Node *jtnode,
 {
 	Query	   *parse = root->parse;
 	RangeTblFunction *rtf;
+	TypeFuncClass functypclass;
+	Oid			funcrettype;
+	TupleDesc	tupdesc;
 	pullup_replace_vars_context rvcontext;
 
 	/* Fail if the RTE has ORDINALITY - we don't implement that here. */
@@ -1696,6 +1700,20 @@ pull_up_constant_function(PlannerInfo *root, Node *jtnode,
 	if (!IsA(rtf->funcexpr, Const))
 		return jtnode;
 
+	/*
+	 * If the function's result is not a scalar, we punt.  In principle we
+	 * could break the composite constant value apart into per-column
+	 * constants, but for now it seems not worth the work.
+	 */
+	if (rtf->funccolcount != 1)
+		return jtnode;			/* definitely composite */
+
+	functypclass = get_expr_result_type(rtf->funcexpr,
+										&funcrettype,
+										&tupdesc);
+	if (functypclass != TYPEFUNC_SCALAR)
+		return jtnode;			/* must be a one-column composite type */
+
 	/* Create context for applying pullup_replace_vars */
 	rvcontext.root = root;
 	rvcontext.targetlist = list_make1(makeTargetEntry((Expr *) rtf->funcexpr,
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 9b407bc4854..b58d560163b 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -3365,6 +3365,43 @@ where nt3.id = 1 and ss2.b3;
 (9 rows)
 
 drop function f_immutable_int4(int);
+-- test inlining when function returns composite
+create function mki8(bigint, bigint) returns int8_tbl as
+$$select row($1,$2)::int8_tbl$$ language sql;
+create function mki4(int) returns int4_tbl as
+$$select row($1)::int4_tbl$$ language sql;
+explain (verbose, costs off)
+select * from mki8(1,2);
+             QUERY PLAN             
+------------------------------------
+ Function Scan on mki8
+   Output: q1, q2
+   Function Call: '(1,2)'::int8_tbl
+(3 rows)
+
+select * from mki8(1,2);
+ q1 | q2 
+----+----
+  1 |  2
+(1 row)
+
+explain (verbose, costs off)
+select * from mki4(42);
+            QUERY PLAN             
+-----------------------------------
+ Function Scan on mki4
+   Output: f1
+   Function Call: '(42)'::int4_tbl
+(3 rows)
+
+select * from mki4(42);
+ f1 
+----
+ 42
+(1 row)
+
+drop function mki8(bigint, bigint);
+drop function mki4(int);
 --
 -- test extraction of restriction OR clauses from join OR clause
 -- (we used to only do this for indexable clauses)
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 145accca86f..57481d04117 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1072,6 +1072,25 @@ where nt3.id = 1 and ss2.b3;
 
 drop function f_immutable_int4(int);
 
+-- test inlining when function returns composite
+
+create function mki8(bigint, bigint) returns int8_tbl as
+$$select row($1,$2)::int8_tbl$$ language sql;
+
+create function mki4(int) returns int4_tbl as
+$$select row($1)::int4_tbl$$ language sql;
+
+explain (verbose, costs off)
+select * from mki8(1,2);
+select * from mki8(1,2);
+
+explain (verbose, costs off)
+select * from mki4(42);
+select * from mki4(42);
+
+drop function mki8(bigint, bigint);
+drop function mki4(int);
+
 --
 -- test extraction of restriction OR clauses from join OR clause
 -- (we used to only do this for indexable clauses)