Fix corner case wherein a WorkTableScan node could get initialized before the

RecursiveUnion to which it refers.  It turns out that we can just postpone the
relevant initialization steps until the first exec call for the node, by which
time the ancestor node must surely be initialized.  Per report from Greg Stark.

2 files changed, 104 insertions, 0 deletions

diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
index 4760aa9d9fd..fe7561065ed 100644
--- a/src/test/regress/expected/with.out
+++ b/src/test/regress/expected/with.out
@@ -292,6 +292,89 @@ SELECT pg_get_viewdef('vsubdepartment'::regclass, true);
     FROM subdepartment;
 (1 row)
 
+-- corner case in which sub-WITH gets initialized first
+with recursive q as (
+      select * from department
+    union all
+      (with x as (select * from q)
+       select * from x)
+    )
+select * from q limit 24;
+ id | parent_department | name 
+----+-------------------+------
+  0 |                   | ROOT
+  1 |                 0 | A
+  2 |                 1 | B
+  3 |                 2 | C
+  4 |                 2 | D
+  5 |                 0 | E
+  6 |                 4 | F
+  7 |                 5 | G
+  0 |                   | ROOT
+  1 |                 0 | A
+  2 |                 1 | B
+  3 |                 2 | C
+  4 |                 2 | D
+  5 |                 0 | E
+  6 |                 4 | F
+  7 |                 5 | G
+  0 |                   | ROOT
+  1 |                 0 | A
+  2 |                 1 | B
+  3 |                 2 | C
+  4 |                 2 | D
+  5 |                 0 | E
+  6 |                 4 | F
+  7 |                 5 | G
+(24 rows)
+
+with recursive q as (
+      select * from department
+    union all
+      (with recursive x as (
+           select * from department
+         union all
+           (select * from q union all select * from x)
+        )
+       select * from x)
+    )
+select * from q limit 32;
+ id | parent_department | name 
+----+-------------------+------
+  0 |                   | ROOT
+  1 |                 0 | A
+  2 |                 1 | B
+  3 |                 2 | C
+  4 |                 2 | D
+  5 |                 0 | E
+  6 |                 4 | F
+  7 |                 5 | G
+  0 |                   | ROOT
+  1 |                 0 | A
+  2 |                 1 | B
+  3 |                 2 | C
+  4 |                 2 | D
+  5 |                 0 | E
+  6 |                 4 | F
+  7 |                 5 | G
+  0 |                   | ROOT
+  1 |                 0 | A
+  2 |                 1 | B
+  3 |                 2 | C
+  4 |                 2 | D
+  5 |                 0 | E
+  6 |                 4 | F
+  7 |                 5 | G
+  0 |                   | ROOT
+  1 |                 0 | A
+  2 |                 1 | B
+  3 |                 2 | C
+  4 |                 2 | D
+  5 |                 0 | E
+  6 |                 4 | F
+  7 |                 5 | G
+(32 rows)
+
 -- recursive term has sub-UNION
 WITH RECURSIVE t(i,j) AS (
 	VALUES (1,2)
diff --git a/src/test/regress/sql/with.sql b/src/test/regress/sql/with.sql
index 60c545d0676..54d311101d1 100644
--- a/src/test/regress/sql/with.sql
+++ b/src/test/regress/sql/with.sql
@@ -178,6 +178,27 @@ SELECT * FROM vsubdepartment ORDER BY name;
 SELECT pg_get_viewdef('vsubdepartment'::regclass);
 SELECT pg_get_viewdef('vsubdepartment'::regclass, true);
 
+-- corner case in which sub-WITH gets initialized first
+with recursive q as (
+      select * from department
+    union all
+      (with x as (select * from q)
+       select * from x)
+    )
+select * from q limit 24;
+
+with recursive q as (
+      select * from department
+    union all
+      (with recursive x as (
+           select * from department
+         union all
+           (select * from q union all select * from x)
+        )
+       select * from x)
+    )
+select * from q limit 32;
+
 -- recursive term has sub-UNION
 WITH RECURSIVE t(i,j) AS (
 	VALUES (1,2)