Fixed bug #57024.

The condition over the outer tables now are extracted from
the on condition of any outer join. This condition is
saved in a special field of the JOIN_TAB structure for
the first inner table of the outer join. The condition
is checked before the first inner table is accessed. If 
it turns out to be false the table is not accessed at all
and a null complemented row is generated immediately.

1 files changed, 44 insertions, 0 deletions

diff --git a/mysql-test/t/join_outer.test b/mysql-test/t/join_outer.test
index cbc65d66624..6d1ef15337f 100644
--- a/mysql-test/t/join_outer.test
+++ b/mysql-test/t/join_outer.test
@@ -1029,4 +1029,48 @@ select t2.pk,
 
 drop table t1,t2,t3,t4;
 
+--echo #
+--echo # Bug#57024: Poor performance when conjunctive condition over the outer 
+--echo #            table is used in the on condition of an outer join
+--echo # 
+
+create table t1 (a int);
+insert into t1 values (NULL), (NULL), (NULL), (NULL);
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 select * from t1; 
+insert into t1 values (4), (2), (1), (3);
+
+create table t2 like t1;
+insert into t2 select if(t1.a is null, 10, t1.a) from t1;
+
+create table t3 (a int, b int, index idx(a));  
+insert into t3 values (1, 100), (3, 301), (4, 402), (1, 102), (1, 101);
+
+analyze table t1,t2,t3;
+
+flush status;
+select sum(t3.b) from t1 left join t3 on t3.a=t1.a and t1.a is not null;
+show status like "handler_read%";
+flush status;
+select sum(t3.b) from t2 left join t3 on t3.a=t2.a and t2.a <> 10;
+show status like "handler_read%";
+
+drop table t1,t2,t3;
+
 --echo End of 5.1 tests