MDEV-14297: Lost name of a explicitly named CTE column used in

            the non-recursive CTE via prepared statement

The problem appears as the column names of the CTE were allocated on the
wrong MEMROOT and after the preparation of the statement they disappear.

To fix it in the procedure With_element::rename_columns_of_derived_unit
the CTE column names are now allocated in the permanent MEMROOT for the
prepared statements and stored procedures.

1 files changed, 7 insertions, 0 deletions

diff --git a/sql/sql_cte.cc b/sql/sql_cte.cc
index ac27f1713f9..dd46295d799 100644
--- a/sql/sql_cte.cc
+++ b/sql/sql_cte.cc
@@ -910,12 +910,19 @@ With_element::rename_columns_of_derived_unit(THD *thd,
       my_error(ER_WITH_COL_WRONG_LIST, MYF(0));
       return true;
     }
+
+    Query_arena *arena, backup;
+    arena= thd->activate_stmt_arena_if_needed(&backup);
+
     /* Rename the columns of the first select in the unit */
     while ((item= it++, name= nm++))
     {
       item->set_name(thd, name->str, (uint) name->length, system_charset_info);
       item->is_autogenerated_name= false;
     }
+
+    if (arena)
+      thd->restore_active_arena(arena, &backup);
   }
   else
     make_valid_column_names(thd, select->item_list);