2 files changed, 38 insertions, 0 deletions
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index ddc4e692329..b60f5a67c1e 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -4133,6 +4133,32 @@ select * from mki4(42);
 
 drop function mki8(bigint, bigint);
 drop function mki4(int);
+-- test const-folding of a whole-row Var into a per-field Var
+-- (need to inline a function to reach this case, else parser does it)
+create function f_field_select(t onek) returns int4 as
+$$ select t.unique2; $$ language sql immutable;
+explain (verbose, costs off)
+select (t2.*).unique1, f_field_select(t2) from tenk1 t1
+    left join onek t2 on t1.unique1 = t2.unique1
+    left join int8_tbl t3 on true;
+                             QUERY PLAN                             
+--------------------------------------------------------------------
+ Nested Loop Left Join
+   Output: t2.unique1, t2.unique2
+   ->  Hash Left Join
+         Output: t2.unique1, t2.unique2
+         Hash Cond: (t1.unique1 = t2.unique1)
+         ->  Index Only Scan using tenk1_unique1 on public.tenk1 t1
+               Output: t1.unique1
+         ->  Hash
+               Output: t2.unique1, t2.unique2
+               ->  Seq Scan on public.onek t2
+                     Output: t2.unique1, t2.unique2
+   ->  Materialize
+         ->  Seq Scan on public.int8_tbl t3
+(13 rows)
+
+drop function f_field_select(t onek);
 --
 -- 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 a41787d1f1e..fbaee480d32 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1381,6 +1381,18 @@ select * from mki4(42);
 drop function mki8(bigint, bigint);
 drop function mki4(int);
 
+-- test const-folding of a whole-row Var into a per-field Var
+-- (need to inline a function to reach this case, else parser does it)
+create function f_field_select(t onek) returns int4 as
+$$ select t.unique2; $$ language sql immutable;
+
+explain (verbose, costs off)
+select (t2.*).unique1, f_field_select(t2) from tenk1 t1
+    left join onek t2 on t1.unique1 = t2.unique1
+    left join int8_tbl t3 on true;
+
+drop function f_field_select(t onek);
+
 --
 -- test extraction of restriction OR clauses from join OR clause
 -- (we used to only do this for indexable clauses)