MDEV-3914 fix.

Fixed algorithm of detecting of first real table in view/subquery-in-the-FROM-clase.

mysql-test/r/view.result

@@ -4568,6 +4568,30 @@ id	id	bbb	iddqd	val1
 drop view v2;
 drop table t1,t2;
 #
+# MDEV-3914: Wrong result (NULLs instead of real values)
+# with INNER and RIGHT JOIN in a FROM subquery, derived_merge=on
+# (fix of above MDEV-486 fix)
+#
+SET @save_optimizer_switch_MDEV_3914=@@optimizer_switch;
+SET optimizer_switch = 'derived_merge=on';
+CREATE TABLE t1 (a INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (b INT) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (c INT) ENGINE=MyISAM;
+INSERT INTO t3 VALUES (5),(6);
+SELECT * FROM ( SELECT c FROM ( t1 INNER JOIN t2 ) RIGHT JOIN t3 ON a = c ) AS alias;
+c
+5
+6
+SET optimizer_switch = 'derived_merge=off';
+SELECT * FROM ( SELECT c FROM ( t1 INNER JOIN t2 ) RIGHT JOIN t3 ON a = c ) AS alias;
+c
+5
+6
+SET optimizer_switch=@save_optimizer_switch_MDEV_3914;
+drop table t1,t2,t3;
+#
 # MDEV-589 (LP BUG#1007647) :
 # Assertion `vcol_table == 0 || vcol_table == table' failed in
 # fill_record(THD*, List<Item>&, List<Item>&, bool)

mysql-test/t/view.test

@@ -4504,6 +4504,32 @@ select t1.*, v2.* from t1 left join v2 on t1.id = v2.id;
 drop view v2;
 drop table t1,t2;
 
+--echo #
+--echo # MDEV-3914: Wrong result (NULLs instead of real values)
+--echo # with INNER and RIGHT JOIN in a FROM subquery, derived_merge=on
+--echo # (fix of above MDEV-486 fix)
+--echo #
+SET @save_optimizer_switch_MDEV_3914=@@optimizer_switch;
+SET optimizer_switch = 'derived_merge=on';
+
+CREATE TABLE t1 (a INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+
+CREATE TABLE t2 (b INT) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (3),(4);
+
+CREATE TABLE t3 (c INT) ENGINE=MyISAM;
+INSERT INTO t3 VALUES (5),(6);
+
+SELECT * FROM ( SELECT c FROM ( t1 INNER JOIN t2 ) RIGHT JOIN t3 ON a = c ) AS alias;
+
+SET optimizer_switch = 'derived_merge=off';
+
+SELECT * FROM ( SELECT c FROM ( t1 INNER JOIN t2 ) RIGHT JOIN t3 ON a = c ) AS alias;
+
+SET optimizer_switch=@save_optimizer_switch_MDEV_3914;
+drop table t1,t2,t3;
+
 --echo #
 --echo # MDEV-589 (LP BUG#1007647) :
 --echo # Assertion `vcol_table == 0 || vcol_table == table' failed in

sql/table.cc

@@ -4457,19 +4457,33 @@ TABLE *TABLE_LIST::get_real_join_table()
     DBUG_ASSERT(tbl->derived == NULL ||
                tbl->derived->first_select()->next_select() == NULL);
 
-    if (tbl->table)
-      table= tbl->table;
-    tbl= (tbl->view != NULL ?
-          tbl->view->select_lex.get_table_list() :
-          tbl->derived->first_select()->get_table_list());
-
-    /* find left table in outer join on this level */
-    while(tbl->outer_join & JOIN_TYPE_RIGHT)
     {
-      DBUG_ASSERT(tbl->next_local);
-      tbl= tbl->next_local;
+      List_iterator_fast<TABLE_LIST> ti;
+      {
+        List_iterator_fast<TABLE_LIST>
+          ti(tbl->view != NULL ?
+             tbl->view->select_lex.top_join_list :
+             tbl->derived->first_select()->top_join_list);
+        for (;;)
+        {
+          tbl= NULL;
+          /*
+            Find left table in outer join on this level
+            (the list is reverted).
+          */
+          for (TABLE_LIST *t= ti++; t; t= ti++)
+            tbl= t;
+          /*
+            It is impossible that the list is empty
+            so tbl can't be NULL after above loop.
+          */
+          if (!tbl->nested_join)
+            break;
+          /* go deeper if we've found nested join */
+          ti= tbl->nested_join->join_list;
+        }
+      }
     }
-
   }
 
   return tbl->table;