Fixed bug in SQL_SELECT_LIMIT

We where comparing costs when we should be comparing number of rows
that will be examined

mysql-test/suite/sys_vars/r/max_join_size_func.result

@@ -39,19 +39,19 @@ id	name	id	name
 connect  test_con1, localhost, root,,;
 connection test_con1;
 ## Setting value of max_join_size ## 
-SET @@session.max_join_size=8;
+SET @@session.max_join_size=4;
 ## Since total joins are more than max_join_size value so error will occur ##
 SELECT * FROM t1 INNER JOIN t2 ON t1.id = t2.id;
 ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay
 '#--------------------FN_DYNVARS_079_03-------------------------#'
 ## Setting global value of variable ##
-SET @@global.max_join_size=8;
+SET @@global.max_join_size=4;
 connect  test_con2, localhost, root,,;
 connection test_con2;
 ## Verifying value of max_join_size ##
 SELECT @@global.max_join_size;
 @@global.max_join_size
-8
+4
 ## Since total joins are more than max_join_size value so error will occur ## 
 SELECT * FROM t1 INNER JOIN t2 ON t1.id = t2.id;
 ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay

mysql-test/suite/sys_vars/r/sql_big_selects_func.result

@@ -3,7 +3,7 @@
 SET @session_sql_big_selects = @@SESSION.sql_big_selects;
 SET @session_max_join_size = @@SESSION.max_join_size;
 SET @global_max_join_size = @@GLOBAL.max_join_size;
-SET MAX_JOIN_SIZE=9;
+SET MAX_JOIN_SIZE=21;
 CREATE TEMPORARY TABLE t1(a varchar(20) not null, b varchar(20));
 CREATE TEMPORARY TABLE t2(a varchar(20) null, b varchar(20));
 INSERT INTO t1 VALUES('aa','bb');

mysql-test/suite/sys_vars/t/max_join_size_func.test

@@ -84,7 +84,7 @@ connect (test_con1, localhost, root,,);
 connection test_con1;
 
 --echo ## Setting value of max_join_size ## 
-SET @@session.max_join_size=8;
+SET @@session.max_join_size=4;
 
 --echo ## Since total joins are more than max_join_size value so error will occur ##
 --Error ER_TOO_BIG_SELECT
@@ -97,7 +97,7 @@ SELECT * FROM t1 INNER JOIN t2 ON t1.id = t2.id;
 ##########################################################
 
 --echo ## Setting global value of variable ##
-SET @@global.max_join_size=8;
+SET @@global.max_join_size=4;
 
 connect (test_con2, localhost, root,,);
 connection test_con2;

mysql-test/suite/sys_vars/t/sql_big_selects_func.test

@@ -28,7 +28,7 @@
 SET @session_sql_big_selects = @@SESSION.sql_big_selects;
 SET @session_max_join_size = @@SESSION.max_join_size;
 SET @global_max_join_size = @@GLOBAL.max_join_size;
-SET MAX_JOIN_SIZE=9;
+SET MAX_JOIN_SIZE=21;
 
 #
 # Create tables
@@ -115,8 +115,6 @@ disconnect con_int2;
 #
 # Cleanup
 #
-
-
 SET @@SESSION.sql_big_selects = @session_sql_big_selects;
 SET @@SESSION.max_join_size = @session_max_join_size;
 SET @@GLOBAL.max_join_size = @global_max_join_size;

sql/sql_select.cc

@@ -2621,7 +2621,7 @@ int JOIN::optimize_stage2()
     goto setup_subq_exit;
   }
   if (!(thd->variables.option_bits & OPTION_BIG_SELECTS) &&
-      best_read > (double) thd->variables.max_join_size &&
+      join_record_count > (double) thd->variables.max_join_size &&
       !(select_options & SELECT_DESCRIBE))
   {						/* purecov: inspected */
     my_message(ER_TOO_BIG_SELECT, ER_THD(thd, ER_TOO_BIG_SELECT), MYF(0));