MDEV-20632: Recursive CTE cycle detection using CYCLE clause (nonstandard)

Added CYCLE ... RESTRICT (nonstandard) clause to recursive CTE.

1 files changed, 7 insertions, 4 deletions

diff --git a/sql/sql_cte.h b/sql/sql_cte.h
index 92aca5090f3..4c42dd23614 100644
--- a/sql/sql_cte.h
+++ b/sql/sql_cte.h
@@ -112,6 +112,7 @@ public:
     always empty.
   */
   List <Lex_ident_sys> column_list;
+  List <Lex_ident_sys> *cycle_list;
   /* The query that specifies the table introduced by this with element */
   st_select_lex_unit *spec;
   /* 
@@ -169,7 +170,7 @@ public:
       sq_dep_map(0), work_dep_map(0), mutually_recursive(0),
       top_level_dep_map(0), sq_rec_ref(NULL),
       next_mutually_recursive(NULL), references(0), 
-      query_name(name), column_list(list), spec(unit),
+      query_name(name), column_list(list), cycle_list(0), spec(unit),
       is_recursive(false), rec_outer_references(0), with_anchor(false),
       level(0), rec_result(NULL)
   { unit->with_element= this; }
@@ -206,7 +207,7 @@ public:
 
   void inc_references() { references++; }
 
-  bool rename_columns_of_derived_unit(THD *thd, st_select_lex_unit *unit);
+  bool process_columns_of_derived_unit(THD *thd, st_select_lex_unit *unit);
 
   bool prepare_unreferenced(THD *thd);
 
@@ -214,7 +215,7 @@ public:
                                     table_map &unrestricted,
                                     table_map &encountered);
 
-  void print(String *str, enum_query_type query_type);
+  void print(THD *thd, String *str, enum_query_type query_type);
 
   With_clause *get_owner() { return owner; }
 
@@ -259,6 +260,8 @@ public:
 
   void prepare_for_next_iteration();
 
+  void set_cycle_list(List<Lex_ident_sys> *cycle_list_arg);
+
   friend class With_clause;
 };
 
@@ -353,7 +356,7 @@ public:
 
   void add_unrestricted(table_map map) { unrestricted|= map; }
 
-  void print(String *str, enum_query_type query_type);
+  void print(THD *thd, String *str, enum_query_type query_type);
 
   friend class With_element;