Fixed the bug mdev-12563.

The bug happened when the specification of a recursive CTE had
no recursive references at the top level of the specification.
In this case the regular processing of derived table references
of the select containing a non-recursive reference to this
recursive CTE misses handling the specification unit.
At the preparation stage any non-recursive reference to a
recursive CTE must be handled after the preparation of the
specification unit for this CTE. So we have to force this
preparation when regular handling of derived tables does not
do it.

1 files changed, 59 insertions, 1 deletions

diff --git a/sql/sql_cte.cc b/sql/sql_cte.cc
index 62b27d05e9b..1b14c5b68b7 100644
--- a/sql/sql_cte.cc
+++ b/sql/sql_cte.cc
@@ -141,7 +141,7 @@ bool With_clause::check_dependencies()
 
   /*
     Mark those elements where tables are defined with direct or indirect
-   make recursion.
+    recursion.
   */ 
   for (With_element *with_elem= with_list.first;
        with_elem;
@@ -342,6 +342,8 @@ void With_element::check_dependencies_in_select(st_select_lex *sl,
       tbl->with_internal_reference_map= get_elem_map();
       if (in_subq)
         sq_dep_map|= tbl->with->get_elem_map();
+      else
+        top_level_dep_map|= tbl->with->get_elem_map();
     }
   }
   /* Now look for the dependencies in the subqueries of sl */
@@ -353,6 +355,53 @@ void With_element::check_dependencies_in_select(st_select_lex *sl,
 
 /**
   @brief
+    Find a recursive reference to this with element in subqueries of a select
+ 
+  @param  sel      The select in whose subqueries the reference
+                   to be looked for
+
+  @details
+    The function looks for a recursive reference to this with element in
+    subqueries of select sl. When the first such reference is found
+    it is returned as the result.
+    The function assumes that the identification of all CTE references
+    has been performed earlier.
+
+  @retval
+    Pointer to the found recursive reference if the search succeeded
+    NULL - otherwise 
+*/
+
+TABLE_LIST *With_element::find_first_sq_rec_ref_in_select(st_select_lex *sel)
+{
+  TABLE_LIST *rec_ref= NULL;
+  st_select_lex_unit *inner_unit= sel->first_inner_unit();
+  for (; inner_unit; inner_unit= inner_unit->next_unit())
+  {
+    st_select_lex *sl= inner_unit->first_select();
+    for (; sl; sl= sl->next_select())
+    {
+      for (TABLE_LIST *tbl= sl->table_list.first; tbl; tbl= tbl->next_local)
+      {
+        if (tbl->derived || tbl->nested_join)
+          continue;
+        if (tbl->with && tbl->with->owner== this->owner &&
+            (tbl->with_internal_reference_map & mutually_recursive))
+	{
+	  rec_ref= tbl;
+          return rec_ref;
+        }
+      }
+      if ((rec_ref= find_first_sq_rec_ref_in_select(sl)))
+        return rec_ref;
+    } 
+  }
+  return 0;
+}
+
+
+/**
+  @brief
     Find the dependencies of this element on its siblings in a unit
  
   @param  unit     The unit where to look for the dependencies
@@ -602,6 +651,10 @@ void With_clause::move_anchors_ahead()
   @details
     If the specification of this with element contains anchors the method
     moves them at the very beginning of the specification.
+    Additionally for the other selects of the specification if none of them
+    contains a recursive reference to this with element or a mutually recursive
+    one the method looks for the first such reference in the first recursive 
+    select and set a pointer to it in this->sq_rec_ref.   
 */
 
 void With_element::move_anchors_ahead()
@@ -618,6 +671,11 @@ void With_element::move_anchors_ahead()
       sl->move_node(new_pos);
       new_pos= sl->next_select();
     }
+    else if (!sq_rec_ref && no_rec_ref_on_top_level())
+    {
+      sq_rec_ref= find_first_sq_rec_ref_in_select(sl);
+      DBUG_ASSERT(sq_rec_ref != NULL);
+    }
     last_sl= sl;
   }
   if (spec->union_distinct)