new optimisation for ref_null (SCRUM) (WL#818)

mysql-test/r/subselect.result:
  results of new optimisation
mysql-test/t/subselect.test:
  results of new optimisation
sql/item_cmpfunc.h:
  function type
sql/item_func.h:
  function type
sql/item_subselect.cc:
  new optimisation for ref_or_null
sql/item_subselect.h:
  new optimisation for ref_or_null
sql/sql_select.cc:
  new optimisation for ref_or_null
sql/sql_select.h:
  item_subselect.cc need safe_index_read

1 files changed, 5 insertions, 1 deletions

diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test
index 5a00bf42451..9ceed286063 100644
--- a/mysql-test/t/subselect.test
+++ b/mysql-test/t/subselect.test
@@ -469,7 +469,11 @@ INSERT INTO t1 VALUES (1),(2),(3),(4);
 INSERT INTO t2 VALUES (1),(2),(3);
 SELECT t1.a, t1.a in (select t2.a from t2) FROM t1;
 explain SELECT t1.a, t1.a in (select t2.a from t2) FROM t1;
-drop table t1,t2;
+CREATE TABLE t3 (a int(11) default '0');
+INSERT INTO t3 VALUES (1),(2),(3);
+SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1;
+explain SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1;
+drop table t1,t2,t3;
 
 #LIMIT is not supported now
 create table t1 (a float);