1 files changed, 156 insertions, 0 deletions
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index 6e238e88b37..cc3f5f3737d 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -1154,3 +1154,159 @@ fetch backward all in c1;
 (2 rows)
 
 commit;
+--
+-- Tests for CTE inlining behavior
+--
+-- Basic subquery that can be inlined
+explain (verbose, costs off)
+with x as (select * from (select f1 from subselect_tbl) ss)
+select * from x where f1 = 1;
+            QUERY PLAN            
+----------------------------------
+ Seq Scan on public.subselect_tbl
+   Output: subselect_tbl.f1
+   Filter: (subselect_tbl.f1 = 1)
+(3 rows)
+
+-- Explicitly request materialization
+explain (verbose, costs off)
+with x as materialized (select * from (select f1 from subselect_tbl) ss)
+select * from x where f1 = 1;
+                QUERY PLAN                
+------------------------------------------
+ CTE Scan on x
+   Output: x.f1
+   Filter: (x.f1 = 1)
+   CTE x
+     ->  Seq Scan on public.subselect_tbl
+           Output: subselect_tbl.f1
+(6 rows)
+
+-- Stable functions are safe to inline
+explain (verbose, costs off)
+with x as (select * from (select f1, now() from subselect_tbl) ss)
+select * from x where f1 = 1;
+            QUERY PLAN             
+-----------------------------------
+ Seq Scan on public.subselect_tbl
+   Output: subselect_tbl.f1, now()
+   Filter: (subselect_tbl.f1 = 1)
+(3 rows)
+
+-- Volatile functions prevent inlining
+explain (verbose, costs off)
+with x as (select * from (select f1, random() from subselect_tbl) ss)
+select * from x where f1 = 1;
+                  QUERY PLAN                  
+----------------------------------------------
+ CTE Scan on x
+   Output: x.f1, x.random
+   Filter: (x.f1 = 1)
+   CTE x
+     ->  Seq Scan on public.subselect_tbl
+           Output: subselect_tbl.f1, random()
+(6 rows)
+
+-- SELECT FOR UPDATE cannot be inlined
+explain (verbose, costs off)
+with x as (select * from (select f1 from subselect_tbl for update) ss)
+select * from x where f1 = 1;
+                             QUERY PLAN                             
+--------------------------------------------------------------------
+ CTE Scan on x
+   Output: x.f1
+   Filter: (x.f1 = 1)
+   CTE x
+     ->  Subquery Scan on ss
+           Output: ss.f1
+           ->  LockRows
+                 Output: subselect_tbl.f1, subselect_tbl.ctid
+                 ->  Seq Scan on public.subselect_tbl
+                       Output: subselect_tbl.f1, subselect_tbl.ctid
+(10 rows)
+
+-- Multiply-referenced CTEs are inlined only when requested
+explain (verbose, costs off)
+with x as (select * from (select f1, now() as n from subselect_tbl) ss)
+select * from x, x x2 where x.n = x2.n;
+                QUERY PLAN                 
+-------------------------------------------
+ Merge Join
+   Output: x.f1, x.n, x2.f1, x2.n
+   Merge Cond: (x.n = x2.n)
+   CTE x
+     ->  Seq Scan on public.subselect_tbl
+           Output: subselect_tbl.f1, now()
+   ->  Sort
+         Output: x.f1, x.n
+         Sort Key: x.n
+         ->  CTE Scan on x
+               Output: x.f1, x.n
+   ->  Sort
+         Output: x2.f1, x2.n
+         Sort Key: x2.n
+         ->  CTE Scan on x x2
+               Output: x2.f1, x2.n
+(16 rows)
+
+explain (verbose, costs off)
+with x as not materialized (select * from (select f1, now() as n from subselect_tbl) ss)
+select * from x, x x2 where x.n = x2.n;
+                                 QUERY PLAN                                 
+----------------------------------------------------------------------------
+ Result
+   Output: subselect_tbl.f1, now(), subselect_tbl_1.f1, now()
+   One-Time Filter: (now() = now())
+   ->  Nested Loop
+         Output: subselect_tbl.f1, subselect_tbl_1.f1
+         ->  Seq Scan on public.subselect_tbl
+               Output: subselect_tbl.f1, subselect_tbl.f2, subselect_tbl.f3
+         ->  Materialize
+               Output: subselect_tbl_1.f1
+               ->  Seq Scan on public.subselect_tbl subselect_tbl_1
+                     Output: subselect_tbl_1.f1
+(11 rows)
+
+-- Check handling of outer references
+explain (verbose, costs off)
+with x as (select * from int4_tbl)
+select * from (with y as (select * from x) select * from y) ss;
+         QUERY PLAN          
+-----------------------------
+ Seq Scan on public.int4_tbl
+   Output: int4_tbl.f1
+(2 rows)
+
+explain (verbose, costs off)
+with x as materialized (select * from int4_tbl)
+select * from (with y as (select * from x) select * from y) ss;
+             QUERY PLAN              
+-------------------------------------
+ CTE Scan on x
+   Output: x.f1
+   CTE x
+     ->  Seq Scan on public.int4_tbl
+           Output: int4_tbl.f1
+(5 rows)
+
+-- Ensure that we inline the currect CTE when there are
+-- multiple CTEs with the same name
+explain (verbose, costs off)
+with x as (select 1 as y)
+select * from (with x as (select 2 as y) select * from x) ss;
+ QUERY PLAN  
+-------------
+ Result
+   Output: 2
+(2 rows)
+
+-- Row marks are not pushed into CTEs
+explain (verbose, costs off)
+with x as (select * from subselect_tbl)
+select * from x for update;
+                           QUERY PLAN                           
+----------------------------------------------------------------
+ Seq Scan on public.subselect_tbl
+   Output: subselect_tbl.f1, subselect_tbl.f2, subselect_tbl.f3
+(2 rows)
+