Added thread variable max_seeks_for_key

Change optimizer to prefer key lookups before table scan
Change table scans to be done after tables with constrains on scanned table 


mysql-test/r/distinct.result:
  Update results
mysql-test/r/group_by.result:
  Update results
mysql-test/r/heap.result:
  Update results
mysql-test/r/join.result:
  Update results
mysql-test/r/key_diff.result:
  Update results
mysql-test/r/myisam.result:
  Update results
mysql-test/r/order_by.result:
  Update results
mysql-test/r/select_safe.result:
  Update results
mysql-test/t/distinct.test:
  Change test to be repeatable
mysql-test/t/join.test:
  Change test to be repeatable
mysql-test/t/select_safe.test:
  Add tests for MAX_SEEKS_FOR_KEY
sql/handler.h:
  Optimize structure for 64 bit machines (and to avoid problems with gdb)
sql/item_cmpfunc.cc:
  Initialize not_null_tables_cache properly
sql/mysqld.cc:
  Added max_seeks_for_key
sql/set_var.cc:
  Added max_seeks_for_key
sql/sql_class.h:
  Added max_seeks_for_key
sql/sql_select.cc:
  Added max_seeks_for_key
  Change optimizer to prefer key lookups before table scan.
  Change table scans to be done after tables with constrains on scanned table

1 files changed, 2 insertions, 2 deletions

diff --git a/mysql-test/r/group_by.result b/mysql-test/r/group_by.result
index 94e1ce59585..67e6bec09f6 100644
--- a/mysql-test/r/group_by.result
+++ b/mysql-test/r/group_by.result
@@ -534,11 +534,11 @@ a	b
 explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b;
 table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary; Using filesort
-t2	ALL	a	NULL	NULL	NULL	4	Using where
+t2	ALL	a	NULL	NULL	NULL	3	Using where
 explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b ORDER BY NULL;
 table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary
-t2	ALL	a	NULL	NULL	NULL	4	Using where
+t2	ALL	a	NULL	NULL	NULL	3	Using where
 drop table t1,t2;
 create table t1 (a int, b int);
 insert into t1 values (1, 4),(10, 40),(1, 4),(10, 43),(1, 4),(10, 41),(1, 4),(10, 43),(1, 4);