MWL#17: Table elimination

- Better comments, variable/function renames 

sql/sql_select.cc

@@ -16699,10 +16699,11 @@ static void print_join(THD *thd,
   {
     TABLE_LIST *curr= *tbl;
     /*
-       The (*) check guards againist the case of printing the query for
-       CREATE VIEW. There we'll have nested_join->used_tables==0.
+      The "eliminated_tables &&" check guards againist the case of 
+      printing the query for CREATE VIEW. We do that without having run 
+      JOIN::optimize() and so will have nested_join->used_tables==0.
     */
-    if (eliminated_tables &&  // (*)
+    if (eliminated_tables &&
         ((curr->table && (curr->table->map & eliminated_tables)) ||
          (curr->nested_join && !(curr->nested_join->used_tables &
                                 ~eliminated_tables))))

sql/sql_select.h

@@ -301,6 +301,7 @@ public:
   bool     resume_nested_loop;
   table_map const_table_map,found_const_table_map;
   
+  /* Tables removed by table elimination. Set to 0 before the elimination. */
   table_map eliminated_tables;
   /*
      Bitmap of all inner tables from outer joins