BUG#27939: Early NULLs filtering doesn't work for eq_ref access

 - Turn it on for JT_EQ_REF access method

mysql-test/r/bdb_notembedded.result

+set autocommit=1;
+reset master;
+create table bug16206 (a int);
+insert into bug16206 values(1);
+start transaction;
+insert into bug16206 values(2);
+commit;
+show binlog events;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+f	n	Format_desc	1	n	Server ver: VERSION, Binlog ver: 4
+f	n	Query	1	n	use `test`; create table bug16206 (a int)
+f	n	Query	1	n	use `test`; insert into bug16206 values(1)
+f	n	Query	1	n	use `test`; insert into bug16206 values(2)
+drop table bug16206;
+reset master;
+create table bug16206 (a int) engine=         bdb;
+insert into bug16206 values(0);
+insert into bug16206 values(1);
+start transaction;
+insert into bug16206 values(2);
+commit;
+insert into bug16206 values(3);
+show binlog events;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+f	n	Format_desc	1	n	Server ver: VERSION, Binlog ver: 4
+f	n	Query	1	n	use `test`; create table bug16206 (a int) engine=         bdb
+f	n	Query	1	n	use `test`; insert into bug16206 values(0)
+f	n	Query	1	n	use `test`; insert into bug16206 values(1)
+f	n	Query	1	n	use `test`; BEGIN
+f	n	Query	1	n	use `test`; insert into bug16206 values(2)
+f	n	Query	1	n	use `test`; COMMIT
+f	n	Query	1	n	use `test`; insert into bug16206 values(3)
+drop table bug16206;
+set autocommit=0;
+End of 5.0 tests

mysql-test/r/join.result

@@ -779,4 +779,32 @@ Field	Type	Null	Key	Default	Extra
 Name	varchar(50)	YES		NULL	
 DROP VIEW v1;
 DROP TABLE t1,t2,tv1,tv2;
+create table t1 (a int, b int);
+insert into t1 values 
+(NULL, 1),
+(NULL, 2),
+(NULL, 3),
+(NULL, 4);
+create table t2 (a int not null, primary key(a));
+insert into t2 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+create table t3 (a int not null, primary key(a));
+insert into t3 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+flush status;
+select * from t1, t2, t3 where t3.a=t1.a and t2.a=t1.b;
+a	b	a	a
+explain select * from t1, t2, t3 where t3.a=t1.a and t2.a=t1.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	Using index
+1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
+We expect rnd_next=5, and read_key must be 0 because of short-cutting:
+show status like 'Handler_read%';
+Variable_name	Value
+Handler_read_first	0
+Handler_read_key	0
+Handler_read_next	0
+Handler_read_prev	0
+Handler_read_rnd	0
+Handler_read_rnd_next	5
+drop table t1, t2, t3;
 End of 5.0 tests.

mysql-test/t/bdb_notembedded.test

+-- source include/not_embedded.inc
+-- source include/have_bdb.inc
+
+#
+# Bug #16206: Superfluous COMMIT event in binlog when updating BDB in autocommit mode
+#
+set autocommit=1;
+
+let $VERSION=`select version()`;
+
+reset master;
+create table bug16206 (a int);
+insert into bug16206 values(1);
+start transaction;
+insert into bug16206 values(2);
+commit;
+--replace_result $VERSION VERSION
+--replace_column 1 f 2 n 5 n
+show binlog events;
+drop table bug16206;
+
+reset master;
+create table bug16206 (a int) engine=         bdb;
+insert into bug16206 values(0);
+insert into bug16206 values(1);
+start transaction;
+insert into bug16206 values(2);
+commit;
+insert into bug16206 values(3);
+--replace_result $VERSION VERSION
+--replace_column 1 f 2 n 5 n
+show binlog events;
+drop table bug16206;
+
+set autocommit=0;
+
+
+--echo End of 5.0 tests

mysql-test/t/join.test

@@ -610,4 +610,27 @@ DESCRIBE tv2;
 DROP VIEW v1;
 DROP TABLE t1,t2,tv1,tv2;
 
+
+# BUG#27939: Early NULLs filtering doesn't work for eq_ref access
+create table t1 (a int, b int);
+insert into t1 values 
+  (NULL, 1),
+  (NULL, 2),
+  (NULL, 3),
+  (NULL, 4);
+
+create table t2 (a int not null, primary key(a));
+insert into t2 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+
+create table t3 (a int not null, primary key(a));
+insert into t3 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+
+flush status;
+select * from t1, t2, t3 where t3.a=t1.a and t2.a=t1.b;
+explain select * from t1, t2, t3 where t3.a=t1.a and t2.a=t1.b;
+--echo We expect rnd_next=5, and read_key must be 0 because of short-cutting:
+show status like 'Handler_read%'; 
+drop table t1, t2, t3;
+
+
 --echo End of 5.0 tests.

sql/sql_select.cc

@@ -5444,7 +5444,8 @@ static void add_not_null_conds(JOIN *join)
   for (uint i=join->const_tables ; i < join->tables ; i++)
   {
     JOIN_TAB *tab=join->join_tab+i;
-    if ((tab->type == JT_REF || tab->type == JT_REF_OR_NULL) &&
+    if ((tab->type == JT_REF || tab->type == JT_EQ_REF || 
+         tab->type == JT_REF_OR_NULL) &&
         !tab->table->maybe_null)
     {
       for (uint keypart= 0; keypart < tab->ref.key_parts; keypart++)