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

3 files changed, 15 insertions, 7 deletions

diff --git a/mysql-test/t/distinct.test b/mysql-test/t/distinct.test
index 7f75b6b1687..ecce2409571 100644
--- a/mysql-test/t/distinct.test
+++ b/mysql-test/t/distinct.test
@@ -60,7 +60,7 @@ drop table t1;
 #
 
 CREATE TABLE t1 (a int(10) unsigned not null primary key,b int(10) unsigned);
-INSERT INTO t1 VALUES (1,1),(2,1);
+INSERT INTO t1 VALUES (1,1),(2,1),(3,1),(4,1);
 CREATE TABLE t2 (a int(10) unsigned not null, key (A));
 INSERT INTO t2 VALUES (1),(2);
 CREATE TABLE t3 (a int(10) unsigned, key(A), b text);
diff --git a/mysql-test/t/join.test b/mysql-test/t/join.test
index 08cc5731723..19e04d2aa7e 100644
--- a/mysql-test/t/join.test
+++ b/mysql-test/t/join.test
@@ -98,10 +98,7 @@ CREATE TABLE t2 (
 INSERT INTO t2 VALUES (3,2,11,12,5400,7800);
 INSERT INTO t2 VALUES (4,2,25,12,6500,11200);
 INSERT INTO t2 VALUES (5,1,37,6,10000,12000);
-
-select a.id, b.category as catid, b.state as stateid, b.county as
-countyid from t1 a, t2 b where (a.token =
-'a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
+select a.id, b.category as catid, b.state as stateid, b.county as countyid from t1 a, t2 b ignore index (primary) where (a.token ='a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
 select a.id, b.category as catid, b.state as stateid, b.county as
 countyid from t1 a, t2 b where (a.token =
 'a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id) order by a.id;
diff --git a/mysql-test/t/select_safe.test b/mysql-test/t/select_safe.test
index a085cfee29d..049a35aa355 100644
--- a/mysql-test/t/select_safe.test
+++ b/mysql-test/t/select_safe.test
@@ -4,7 +4,7 @@
 
 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;
 update t1 set b="a" where a=1;
@@ -12,7 +12,7 @@ delete from t1 where a=1;
 insert into t1 values(1,"test"),(2,"test2");
 SELECT SQL_BUFFER_RESULT * from t1;
 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;
 
 # The following should give errors:
 --error 1175
@@ -49,6 +49,17 @@ SELECT * from t1;
 SET MAX_JOIN_SIZE=DEFAULT;
 SELECT * from t1;
 
+#
+# Test MAX_SEEKS_FOR_KEY
+#
+SELECT @@MAX_SEEKS_FOR_KEY;
+analyze table t1;
+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;
+set MAX_SEEKS_FOR_KEY=1;
+explain select * from t1,t1 as t2 where t1.b=t2.b;
+SET MAX_SEEKS_FOR_KEY=DEFAULT;
+
 drop table t1;
 
 SET SQL_SAFE_UPDATES=0,SQL_SELECT_LIMIT=DEFAULT, SQL_MAX_JOIN_SIZE=DEFAULT;