Enhanced cycle mark values

Per SQL:202x draft, in the CYCLE clause of a recursive query, the
cycle mark values can be of type boolean and can be omitted, in which
case they default to TRUE and FALSE.

Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Discussion: https://www.postgresql.org/message-id/flat/db80ceee-6f97-9b4a-8ee8-3ba0c58e5be2@2ndquadrant.com

src/backend/catalog/sql_features.txt

@@ -425,6 +425,7 @@ T121	WITH (excluding RECURSIVE) in query expression			YES
 T122	WITH (excluding RECURSIVE) in subquery			YES	
 T131	Recursive query			YES	
 T132	Recursive query in subquery			YES	
+T133	Enhanced cycle mark values			YES	SQL:202x draft
 T141	SIMILAR predicate			YES	
 T151	DISTINCT predicate			YES	
 T152	DISTINCT predicate with negation			YES	

src/backend/parser/gram.y

@@ -11442,6 +11442,17 @@ opt_cycle_clause:
 				n->location = @1;
 				$$ = (Node *) n;
 			}
+		| CYCLE columnList SET ColId USING ColId
+			{
+				CTECycleClause *n = makeNode(CTECycleClause);
+				n->cycle_col_list = $2;
+				n->cycle_mark_column = $4;
+				n->cycle_mark_value = makeBoolAConst(true, -1);
+				n->cycle_mark_default = makeBoolAConst(false, -1);
+				n->cycle_path_column = $6;
+				n->location = @1;
+				$$ = (Node *) n;
+			}
 		| /*EMPTY*/
 			{
 				$$ = NULL;

src/backend/utils/adt/ruleutils.c

@@ -5208,10 +5208,21 @@ get_with_clause(Query *query, deparse_context *context)
 			}
 
 			appendStringInfo(buf, " SET %s", quote_identifier(cte->cycle_clause->cycle_mark_column));
-			appendStringInfoString(buf, " TO ");
-			get_rule_expr(cte->cycle_clause->cycle_mark_value, context, false);
-			appendStringInfoString(buf, " DEFAULT ");
-			get_rule_expr(cte->cycle_clause->cycle_mark_default, context, false);
+
+			{
+				Const	   *cmv = castNode(Const, cte->cycle_clause->cycle_mark_value);
+				Const	   *cmd = castNode(Const, cte->cycle_clause->cycle_mark_default);
+
+				if (!(cmv->consttype == BOOLOID && !cmv->constisnull && DatumGetBool(cmv->constvalue) == true &&
+					  cmd->consttype == BOOLOID && !cmd->constisnull && DatumGetBool(cmd->constvalue) == false))
+				{
+					appendStringInfoString(buf, " TO ");
+					get_rule_expr(cte->cycle_clause->cycle_mark_value, context, false);
+					appendStringInfoString(buf, " DEFAULT ");
+					get_rule_expr(cte->cycle_clause->cycle_mark_default, context, false);
+				}
+			}
+
 			appendStringInfo(buf, " USING %s", quote_identifier(cte->cycle_clause->cycle_path_column));
 		}
 

src/test/regress/expected/with.out

@@ -951,7 +951,7 @@ with recursive search_graph(f, t, label) as (
 	select g.*
 	from graph g, search_graph sg
 	where g.f = sg.t
-) cycle f, t set is_cycle to true default false using path
+) cycle f, t set is_cycle using path
 select * from search_graph;
  f | t |   label    | is_cycle |                   path                    
 ---+---+------------+----------+-------------------------------------------
@@ -1071,7 +1071,7 @@ with recursive a as (
 	select 1 as b
 	union all
 	select * from a
-) cycle b set c to true default false using p
+) cycle b set c using p
 select * from a;
  b | c |     p     
 ---+---+-----------
@@ -1087,7 +1087,7 @@ with recursive search_graph(f, t, label) as (
 	from graph g, search_graph sg
 	where g.f = sg.t
 ) search depth first by f, t set seq
-  cycle f, t set is_cycle to true default false using path
+  cycle f, t set is_cycle using path
 select * from search_graph;
  f | t |   label    |                    seq                    | is_cycle |                   path                    
 ---+---+------------+-------------------------------------------+----------+-------------------------------------------
@@ -1125,7 +1125,7 @@ with recursive search_graph(f, t, label) as (
 	from graph g, search_graph sg
 	where g.f = sg.t
 ) search breadth first by f, t set seq
-  cycle f, t set is_cycle to true default false using path
+  cycle f, t set is_cycle using path
 select * from search_graph;
  f | t |   label    |   seq   | is_cycle |                   path                    
 ---+---+------------+---------+----------+-------------------------------------------
@@ -1163,10 +1163,10 @@ with recursive search_graph(f, t, label) as (
 	select g.*
 	from graph g, search_graph sg
 	where g.f = sg.t
-) cycle foo, tar set is_cycle to true default false using path
+) cycle foo, tar set is_cycle using path
 select * from search_graph;
 ERROR:  cycle column "foo" not in WITH query column list
-LINE 7: ) cycle foo, tar set is_cycle to true default false using pa...
+LINE 7: ) cycle foo, tar set is_cycle using path
           ^
 with recursive search_graph(f, t, label) as (
 	select * from graph g
@@ -1257,38 +1257,99 @@ ERROR:  search_sequence column name and cycle path column name are the same
 LINE 7: ) search depth first by f, t set foo
           ^
 -- test ruleutils and view expansion
-create temp view v_cycle as
+create temp view v_cycle1 as
 with recursive search_graph(f, t, label) as (
 	select * from graph g
 	union all
 	select g.*
 	from graph g, search_graph sg
 	where g.f = sg.t
-) cycle f, t set is_cycle to true default false using path
+) cycle f, t set is_cycle using path
 select f, t, label from search_graph;
-select pg_get_viewdef('v_cycle');
-                           pg_get_viewdef                           
---------------------------------------------------------------------
-  WITH RECURSIVE search_graph(f, t, label) AS (                    +
-          SELECT g.f,                                              +
-             g.t,                                                  +
-             g.label                                               +
-            FROM graph g                                           +
-         UNION ALL                                                 +
-          SELECT g.f,                                              +
-             g.t,                                                  +
-             g.label                                               +
-            FROM graph g,                                          +
-             search_graph sg                                       +
-           WHERE (g.f = sg.t)                                      +
-         ) CYCLE f, t SET is_cycle TO true DEFAULT false USING path+
-  SELECT search_graph.f,                                           +
-     search_graph.t,                                               +
-     search_graph.label                                            +
+create temp view v_cycle2 as
+with recursive search_graph(f, t, label) as (
+	select * from graph g
+	union all
+	select g.*
+	from graph g, search_graph sg
+	where g.f = sg.t
+) cycle f, t set is_cycle to 'Y' default 'N' using path
+select f, t, label from search_graph;
+select pg_get_viewdef('v_cycle1');
+                 pg_get_viewdef                 
+------------------------------------------------
+  WITH RECURSIVE search_graph(f, t, label) AS (+
+          SELECT g.f,                          +
+             g.t,                              +
+             g.label                           +
+            FROM graph g                       +
+         UNION ALL                             +
+          SELECT g.f,                          +
+             g.t,                              +
+             g.label                           +
+            FROM graph g,                      +
+             search_graph sg                   +
+           WHERE (g.f = sg.t)                  +
+         ) CYCLE f, t SET is_cycle USING path  +
+  SELECT search_graph.f,                       +
+     search_graph.t,                           +
+     search_graph.label                        +
     FROM search_graph;
 (1 row)
 
-select * from v_cycle;
+select pg_get_viewdef('v_cycle2');
+                               pg_get_viewdef                                
+-----------------------------------------------------------------------------
+  WITH RECURSIVE search_graph(f, t, label) AS (                             +
+          SELECT g.f,                                                       +
+             g.t,                                                           +
+             g.label                                                        +
+            FROM graph g                                                    +
+         UNION ALL                                                          +
+          SELECT g.f,                                                       +
+             g.t,                                                           +
+             g.label                                                        +
+            FROM graph g,                                                   +
+             search_graph sg                                                +
+           WHERE (g.f = sg.t)                                               +
+         ) CYCLE f, t SET is_cycle TO 'Y'::text DEFAULT 'N'::text USING path+
+  SELECT search_graph.f,                                                    +
+     search_graph.t,                                                        +
+     search_graph.label                                                     +
+    FROM search_graph;
+(1 row)
+
+select * from v_cycle1;
+ f | t |   label    
+---+---+------------
+ 1 | 2 | arc 1 -> 2
+ 1 | 3 | arc 1 -> 3
+ 2 | 3 | arc 2 -> 3
+ 1 | 4 | arc 1 -> 4
+ 4 | 5 | arc 4 -> 5
+ 5 | 1 | arc 5 -> 1
+ 1 | 2 | arc 1 -> 2
+ 1 | 3 | arc 1 -> 3
+ 1 | 4 | arc 1 -> 4
+ 2 | 3 | arc 2 -> 3
+ 4 | 5 | arc 4 -> 5
+ 5 | 1 | arc 5 -> 1
+ 1 | 2 | arc 1 -> 2
+ 1 | 3 | arc 1 -> 3
+ 1 | 4 | arc 1 -> 4
+ 2 | 3 | arc 2 -> 3
+ 4 | 5 | arc 4 -> 5
+ 5 | 1 | arc 5 -> 1
+ 1 | 2 | arc 1 -> 2
+ 1 | 3 | arc 1 -> 3
+ 1 | 4 | arc 1 -> 4
+ 2 | 3 | arc 2 -> 3
+ 4 | 5 | arc 4 -> 5
+ 5 | 1 | arc 5 -> 1
+ 2 | 3 | arc 2 -> 3
+(25 rows)
+
+select * from v_cycle2;
  f | t |   label    
 ---+---+------------
  1 | 2 | arc 1 -> 2

src/test/regress/sql/with.sql

@@ -509,7 +509,7 @@ with recursive search_graph(f, t, label) as (
 	select g.*
 	from graph g, search_graph sg
 	where g.f = sg.t
-) cycle f, t set is_cycle to true default false using path
+) cycle f, t set is_cycle using path
 select * from search_graph;
 
 with recursive search_graph(f, t, label) as (
@@ -545,7 +545,7 @@ with recursive a as (
 	select 1 as b
 	union all
 	select * from a
-) cycle b set c to true default false using p
+) cycle b set c using p
 select * from a;
 
 -- search+cycle
@@ -556,7 +556,7 @@ with recursive search_graph(f, t, label) as (
 	from graph g, search_graph sg
 	where g.f = sg.t
 ) search depth first by f, t set seq
-  cycle f, t set is_cycle to true default false using path
+  cycle f, t set is_cycle using path
 select * from search_graph;
 
 with recursive search_graph(f, t, label) as (
@@ -566,7 +566,7 @@ with recursive search_graph(f, t, label) as (
 	from graph g, search_graph sg
 	where g.f = sg.t
 ) search breadth first by f, t set seq
-  cycle f, t set is_cycle to true default false using path
+  cycle f, t set is_cycle using path
 select * from search_graph;
 
 -- various syntax errors
@@ -576,7 +576,7 @@ with recursive search_graph(f, t, label) as (
 	select g.*
 	from graph g, search_graph sg
 	where g.f = sg.t
-) cycle foo, tar set is_cycle to true default false using path
+) cycle foo, tar set is_cycle using path
 select * from search_graph;
 
 with recursive search_graph(f, t, label) as (
@@ -654,19 +654,31 @@ with recursive search_graph(f, t, label) as (
 select * from search_graph;
 
 -- test ruleutils and view expansion
-create temp view v_cycle as
+create temp view v_cycle1 as
 with recursive search_graph(f, t, label) as (
 	select * from graph g
 	union all
 	select g.*
 	from graph g, search_graph sg
 	where g.f = sg.t
-) cycle f, t set is_cycle to true default false using path
+) cycle f, t set is_cycle using path
 select f, t, label from search_graph;
 
-select pg_get_viewdef('v_cycle');
+create temp view v_cycle2 as
+with recursive search_graph(f, t, label) as (
+	select * from graph g
+	union all
+	select g.*
+	from graph g, search_graph sg
+	where g.f = sg.t
+) cycle f, t set is_cycle to 'Y' default 'N' using path
+select f, t, label from search_graph;
 
-select * from v_cycle;
+select pg_get_viewdef('v_cycle1');
+select pg_get_viewdef('v_cycle2');
+
+select * from v_cycle1;
+select * from v_cycle2;
 
 --
 -- test multiple WITH queries