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, 19 insertions, 4 deletions

diff --git a/mysql-test/r/select_safe.result b/mysql-test/r/select_safe.result
index 3303f19d9c7..830390ebe3c 100644
--- a/mysql-test/r/select_safe.result
+++ b/mysql-test/r/select_safe.result
@@ -1,6 +1,6 @@
 drop table if exists t1;
 SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=4, SQL_MAX_JOIN_SIZE=9;
-create table t1 (a int auto_increment primary key, b char(20));
+create table t1 (a int auto_increment primary key, b char(20), key(b));
 insert into t1 values(1,"test");
 SELECT SQL_BUFFER_RESULT * from t1;
 a	b
@@ -13,7 +13,7 @@ a	b
 1	test
 2	test2
 update t1 set b="a" where a=1;
-select 1 from t1,t1 as t2,t1 as t3,t1 as t4;
+select 1 from t1,t1 as t2,t1 as t3;
 1
 1
 1
@@ -22,11 +22,9 @@ select 1 from t1,t1 as t2,t1 as t3,t1 as t4;
 update t1 set b="a";
 You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
 update t1 set b="a" where b="test";
-You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
 delete from t1;
 You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
 delete from t1 where b="test";
-You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
 delete from t1 where a+0=1;
 You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
 select 1 from t1,t1 as t2,t1 as t3,t1 as t4,t1 as t5;
@@ -59,5 +57,22 @@ a	b
 2	test2
 4	a
 5	a
+SELECT @@MAX_SEEKS_FOR_KEY;
+@@max_seeks_for_key
+4294967295
+analyze table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
+explain select * from t1,t1 as t2 where t1.b=t2.b;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	ALL	b	NULL	NULL	NULL	21	
+t2	ALL	b	NULL	NULL	NULL	16	Using where
+set MAX_SEEKS_FOR_KEY=1;
+explain select * from t1,t1 as t2 where t1.b=t2.b;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	ALL	b	NULL	NULL	NULL	21	
+t2	ref	b	b	21	t1.b	6	Using where
+SET MAX_SEEKS_FOR_KEY=DEFAULT;
 drop table t1;
 SET SQL_SAFE_UPDATES=0,SQL_SELECT_LIMIT=DEFAULT, SQL_MAX_JOIN_SIZE=DEFAULT;