total table list managment is changed

1 files changed, 9 insertions, 1 deletions

diff --git a/sql/table.h b/sql/table.h
index e30e29ddd3f..1c65c2a7ce2 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -143,7 +143,15 @@ typedef struct st_table_list {
   struct st_table_list *natural_join;	 /* natural join on this table*/
   /* ... join ... USE INDEX ... IGNORE INDEX */
   List<String>	*use_index, *ignore_index; 
-  TABLE		*table;
+  /*
+    Usually hold reference on opened table, but may hold reference
+    to node of complete list of tables used in UNION & subselect.
+  */
+  union
+  {
+    TABLE          *table;      /* opened table */
+    st_table_list  *table_list; /* pointer to node of list of all tables */
+  };
   GRANT_INFO	grant;
   thr_lock_type lock_type;
   uint		outer_join;		 /* Which join type */