Bug#21067109: Assert 'join == __NULL' failed in ::optimize()

Patch # 4 of 5

Currently, optimize_cond() builds multiple equalities for all WHERE
conditions and all join conditions. But there is one omission: If
WHERE condition is NULL, then no multiple equalities are built for
any join conditions.

This patch fixes that problem by the following logic:
- Invoke optimize_cond() when we have a WHERE condition or an outer join
  (an outer join usually implies at least one join condition).
- Inside optimize_cond(), call build_equal_items() whenever there is a
  join list (ie this is not called for HAVING).
- build_equal_items() then inspects the WHERE clause and the various
  join conditions, and analyzes any conditions that are not NULL.

There are several test changes due to this patch. Most changes just
reverse the order that operands are tested, this is due to the nature
of multiple equality processing. The more interesting test changes are
documented below.

Test change in main.subquery_sj_all:

 select * from t1 left join t2 on (t2.A= t1.A And t2.A in (select pk from t10));

Due to multiple equality analysis, a table with REF access is shifted up
so that it can be evaluated before a table where table scan is applied.

 SELECT *
 FROM ot1 LEFT JOIN ot2 ON ot1.a=ot2.a AND
 (ot1.a, ot2.a) IN (SELECT it1.a, it2.a

Due to multiple equality analysis, a join condition can be evaluated earlier
than it used to be.

Test change in main.derived:

  SELECT * FROM (SELECT v1.a
                 FROM v1 LEFT OUTER JOIN v2 ON v1.a = v2.b
                 WHERE v1.a = 3
                 GROUP BY v1.a) p, t q
  WHERE q.id BETWEEN 1 AND 10;

Due to the multiple equality analysis, a "func" ref is changed to a "const",
which is slightly simpler to evaluate.

Test change in main.join_nested:

Two queries have a WHERE clause moved from third to second table in
join order.

Test change in main.join_outer:

Comparison against column is replaced with comparison against literal due
to multiple equality analysis.

Author: roylyseng

mysql-test/r/derived.result

@@ -3048,7 +3048,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	no matching row in const table
 4	DEPENDENT SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	no matching row in const table
 Warnings:
-Note	1003	/* select#1 */ select `test`.`sq1_t1`.`pk` AS `field1`,`test`.`sq2_t1`.`pk` AS `field2` from `test`.`t2` `table3` left join (`test`.`t2` `sq2_t1`) on(((NULL = `test`.`sq2_t1`.`col_varchar_key`) and (not(<in_optimizer>(`test`.`sq2_t1`.`col_int_key`,<exists>(/* select#4 */ select 1 from `test`.`t2` `child_sq1_t1` where <if>(outer_field_is_not_null, ((<cache>(`test`.`sq2_t1`.`col_int_key`) = NULL) or isnull(NULL)), true) having <if>(outer_field_is_not_null, <is_not_null_test>(NULL), true))))))) left join (`test`.`t1` `sq1_t1`) on((NULL = `test`.`sq2_t1`.`col_varchar_key`))
+Note	1003	/* select#1 */ select `test`.`sq1_t1`.`pk` AS `field1`,`test`.`sq2_t1`.`pk` AS `field2` from `test`.`t2` `table3` left join (`test`.`t2` `sq2_t1`) on(((not(<in_optimizer>(`test`.`sq2_t1`.`col_int_key`,<exists>(/* select#4 */ select 1 from `test`.`t2` `child_sq1_t1` where <if>(outer_field_is_not_null, ((<cache>(`test`.`sq2_t1`.`col_int_key`) = NULL) or isnull(NULL)), true) having <if>(outer_field_is_not_null, <is_not_null_test>(NULL), true))))) and multiple equal(NULL, `test`.`sq2_t1`.`col_varchar_key`))) left join (`test`.`t1` `sq1_t1`) on(multiple equal(NULL, `test`.`sq2_t1`.`col_varchar_key`))
 SELECT table1.pk AS field1,
 table2.pk field2
 FROM (SELECT sq1_t1.*
@@ -3454,9 +3454,9 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	PRIMARY	q	NULL	range	PRIMARY	PRIMARY	4	NULL	4	100.00	Using where
 1	PRIMARY	<derived2>	NULL	ALL	NULL	NULL	NULL	NULL	8	100.00	Using join buffer (Block Nested Loop)
 2	DERIVED	t	NULL	ALL	NULL	NULL	NULL	NULL	4	100.00	Using temporary; Using filesort
-2	DERIVED	t	NULL	ref	c2	c2	5	func	2	100.00	Using where; Using index
+2	DERIVED	t	NULL	ref	c2	c2	5	const	2	100.00	Using where; Using index
 Warnings:
-Note	1003	/* select#1 */ select `p`.`a` AS `a`,`test`.`q`.`id` AS `id`,`test`.`q`.`c1` AS `c1`,`test`.`q`.`c2` AS `c2` from (/* select#2 */ select `test`.`t`.`c1` AS `a` from `test`.`t` left join (`test`.`t`) on(((`test`.`t`.`c1` = `test`.`t`.`c2`) and (`test`.`t`.`c1` = 10) and (`test`.`t`.`c2` > 3))) where 1 group by `test`.`t`.`c1`) `p` join `test`.`t` `q` where (`test`.`q`.`id` between 1 and 10)
+Note	1003	/* select#1 */ select `p`.`a` AS `a`,`test`.`q`.`id` AS `id`,`test`.`q`.`c1` AS `c1`,`test`.`q`.`c2` AS `c2` from (/* select#2 */ select `test`.`t`.`c1` AS `a` from `test`.`t` left join (`test`.`t`) on(((`test`.`t`.`c1` = 10) and (`test`.`t`.`c2` = 10) and (10 > 3))) where 1 group by `test`.`t`.`c1`) `p` join `test`.`t` `q` where (`test`.`q`.`id` between 1 and 10)
 EXPLAIN SELECT * FROM (SELECT v1.a
 FROM v1 LEFT OUTER JOIN v2 ON v1.a = v2.b
 WHERE v1.a = 3

mysql-test/r/distinct.result

@@ -1023,7 +1023,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 2	DERIVED	it_a	NULL	ALL	NULL	NULL	NULL	NULL	2	100.00	NULL
 2	DERIVED	it_b	NULL	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using join buffer (Block Nested Loop)
 Warnings:
-Note	1003	/* select#1 */ select distinct `subselect`.`b` AS `b` from `test`.`t1` left join (/* select#2 */ select `test`.`it_b`.`a` AS `a`,`test`.`it_b`.`b` AS `b` from `test`.`t1` `it_a` left join `test`.`t1` `it_b` on(TRUE) where 1) `subselect` on((`test`.`t1`.`a` = `subselect`.`b`)) where 1
+Note	1003	/* select#1 */ select distinct `subselect`.`b` AS `b` from `test`.`t1` left join (/* select#2 */ select `test`.`it_b`.`a` AS `a`,`test`.`it_b`.`b` AS `b` from `test`.`t1` `it_a` left join `test`.`t1` `it_b` on(TRUE) where 1) `subselect` on((`subselect`.`b` = `test`.`t1`.`a`)) where 1
 SELECT DISTINCT subselect.b
 FROM t1 LEFT JOIN 
 (SELECT it_b.* FROM t1 as it_a LEFT JOIN t1 as it_b ON true) AS subselect 
@@ -1057,7 +1057,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	t3	NULL	const	PRIMARY	NULL	NULL	NULL	1	100.00	Impossible ON condition
 1	SIMPLE	t1	NULL	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Distinct
 Warnings:
-Note	1003	/* select#1 */ select distinct `test`.`t3`.`a` AS `t3_date` from `test`.`t1` left join `test`.`t3` on((NULL = `test`.`t3`.`b`)) where 1 limit 1
+Note	1003	/* select#1 */ select distinct `test`.`t3`.`a` AS `t3_date` from `test`.`t1` left join `test`.`t3` on(multiple equal(NULL, `test`.`t3`.`b`)) where 1 limit 1
 SELECT DISTINCT t3.a AS t3_date
 FROM t1
 LEFT JOIN t2 ON false

mysql-test/r/explain_for_connection_small_json.result

@@ -307,7 +307,7 @@ Diff: EXPLAIN NORMAL vs OTHER
 @@ -49,4 +50,3 @@
              "s1"
 -          ],
--          "attached_condition": "<if>(is_not_null_compl(t2), (`test`.`t1`.`id` = `test`.`t2`.`id`), true)"
+-          "attached_condition": "<if>(is_not_null_compl(t2), (`test`.`t2`.`id` = `test`.`t1`.`id`), true)"
 +          ]
          }
 QUERY: SELECT * from t1 where a = 1 and b is null order by a desc, b desc 

mysql-test/r/explain_json_all.result

@@ -2463,7 +2463,7 @@ EXPLAIN
   } /* query_block */
 }
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,group_concat(`test`.`t2`.`b` separator ',') AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t1`.`a` = `test`.`t2`.`a`)) where 1 group by `test`.`t1`.`a` order by `test`.`t1`.`b`
+Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,group_concat(`test`.`t2`.`b` separator ',') AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`a` = `test`.`t1`.`a`)) where 1 group by `test`.`t1`.`a` order by `test`.`t1`.`b`
 DROP TABLE t1;
 DROP TABLE t2;
 #

mysql-test/r/explain_json_none.result

@@ -2508,7 +2508,7 @@ EXPLAIN
   } /* query_block */
 }
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,group_concat(`test`.`t2`.`b` separator ',') AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t1`.`a` = `test`.`t2`.`a`)) where 1 group by `test`.`t1`.`a` order by `test`.`t1`.`b`
+Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,group_concat(`test`.`t2`.`b` separator ',') AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`a` = `test`.`t1`.`a`)) where 1 group by `test`.`t1`.`a` order by `test`.`t1`.`b`
 DROP TABLE t1;
 DROP TABLE t2;
 #

mysql-test/r/group_by.result

@@ -1967,15 +1967,15 @@ EXPLAIN SELECT MIN(t2.a) FROM t2 LEFT JOIN t1 ON t2.a = t1.a;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
 Warnings:
-Note	1003	/* select#1 */ select min(`test`.`t2`.`a`) AS `MIN(t2.a)` from `test`.`t2` left join `test`.`t1` on((`test`.`t2`.`a` = `test`.`t1`.`a`))
+Note	1003	/* select#1 */ select min(`test`.`t2`.`a`) AS `MIN(t2.a)` from `test`.`t2` left join `test`.`t1` on(multiple equal(`test`.`t2`.`a`, `test`.`t1`.`a`))
 SELECT MIN(t2.a) FROM t2 LEFT JOIN t1 ON t2.a = t1.a;
 MIN(t2.a)
 1
 EXPLAIN SELECT MAX(t2.a) FROM t2 LEFT JOIN t1 ON t2.a = t1.a;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
 Warnings:
-Note	1003	/* select#1 */ select max(`test`.`t2`.`a`) AS `MAX(t2.a)` from `test`.`t2` left join `test`.`t1` on((`test`.`t2`.`a` = `test`.`t1`.`a`))
+Note	1003	/* select#1 */ select max(`test`.`t2`.`a`) AS `MAX(t2.a)` from `test`.`t2` left join `test`.`t1` on(multiple equal(`test`.`t2`.`a`, `test`.`t1`.`a`))
 SELECT MAX(t2.a) FROM t2 LEFT JOIN t1 ON t2.a = t1.a;
 MAX(t2.a)
 2

mysql-test/r/group_by_fd_no_prot.result

@@ -1648,7 +1648,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	emp	NULL	ALL	NULL	NULL	NULL	NULL	1	100.00	Using temporary; Using filesort
 1	SIMPLE	dept	NULL	eq_ref	PRIMARY	PRIMARY	4	test.emp.deptno	1	100.00	NULL
 Warnings:
-Note	1003	/* select#1 */ select `test`.`dept`.`dname` AS `dname`,count(0) AS `COUNT(*)` from `test`.`emp` left join `test`.`dept` on((`test`.`emp`.`deptno` = `test`.`dept`.`deptno`)) where 1 group by `test`.`dept`.`deptno`
+Note	1003	/* select#1 */ select `test`.`dept`.`dname` AS `dname`,count(0) AS `COUNT(*)` from `test`.`emp` left join `test`.`dept` on((`test`.`dept`.`deptno` = `test`.`emp`.`deptno`)) where 1 group by `test`.`dept`.`deptno`
 SELECT dname, COUNT(*)
 FROM empdept
 GROUP BY deptno;

mysql-test/r/group_by_fd_ps_prot.result

@@ -1034,7 +1034,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	emp	NULL	ALL	NULL	NULL	NULL	NULL	1	100.00	Using temporary; Using filesort
 1	SIMPLE	dept	NULL	eq_ref	PRIMARY	PRIMARY	4	test.emp.deptno	1	100.00	NULL
 Warnings:
-Note	1003	/* select#1 */ select `test`.`dept`.`dname` AS `dname`,count(0) AS `COUNT(*)` from `test`.`emp` left join `test`.`dept` on((`test`.`emp`.`deptno` = `test`.`dept`.`deptno`)) where 1 group by `test`.`dept`.`deptno`
+Note	1003	/* select#1 */ select `test`.`dept`.`dname` AS `dname`,count(0) AS `COUNT(*)` from `test`.`emp` left join `test`.`dept` on((`test`.`dept`.`deptno` = `test`.`emp`.`deptno`)) where 1 group by `test`.`dept`.`deptno`
 SELECT dname, COUNT(*)
 FROM empdept
 GROUP BY deptno;

mysql-test/r/internal_tmp_disk_storage_engine.result

@@ -112,15 +112,15 @@ EXPLAIN
               "a",
               "b"
             ],
-            "attached_condition": "<if>(is_not_null_compl(t2), (`test`.`t1`.`b` = `test`.`t2`.`b`), true)"
+            "attached_condition": "<if>(is_not_null_compl(t2), (`test`.`t2`.`b` = `test`.`t1`.`b`), true)"
           }
         }
       ]
     }
   }
 }
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t1`.`b` = `test`.`t2`.`b`)) where 1 order by `test`.`t1`.`a`
+Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`b` = `test`.`t1`.`b`)) where 1 order by `test`.`t1`.`a`
 select * from t1 left join t2 on t1.b = t2.b order by t1.a;
 a	b	a	b
 1	a	NULL	NULL
@@ -1593,15 +1593,15 @@ EXPLAIN
               "a",
               "b"
             ],
-            "attached_condition": "<if>(is_not_null_compl(t2), (`test`.`t1`.`a` = `test`.`t2`.`a`), true)"
+            "attached_condition": "<if>(is_not_null_compl(t2), (`test`.`t2`.`a` = `test`.`t1`.`a`), true)"
           }
         }
       ]
     }
   }
 }
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t1`.`a` = `test`.`t2`.`a`)) where 1 order by `test`.`t1`.`b`
+Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`a` = `test`.`t1`.`a`)) where 1 order by `test`.`t1`.`b`
 select * from t1 left join t2 on t1.a = t2.a order by t1.b;
 a	b	a	b
 1	ababab	NULL	NULL

mysql-test/r/join_cache_bka.result

@@ -1479,7 +1479,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	t1	NULL	index	PRIMARY	PRIMARY	4	NULL	8	100.00	Using index; Using temporary; Using filesort
 1	SIMPLE	t2	NULL	ALL	i_a	NULL	NULL	NULL	10	100.00	Using where; Using join buffer (Block Nested Loop)
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,count(`test`.`t2`.`p`) AS `count` from `test`.`t1` left join `test`.`t2` on(((`test`.`t1`.`a` = `test`.`t2`.`a`) and ((`test`.`t2`.`p` % 2) = 1))) where 1 group by `test`.`t1`.`a`
+Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,count(`test`.`t2`.`p`) AS `count` from `test`.`t1` left join `test`.`t2` on(((`test`.`t2`.`a` = `test`.`t1`.`a`) and ((`test`.`t2`.`p` % 2) = 1))) where 1 group by `test`.`t1`.`a`
 select t1.a, count(t2.p) as count
 from t1 left join t2 on t1.a=t2.a and t2.p % 2 = 1 group by t1.a;
 a	count
@@ -2110,7 +2110,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	t3	NULL	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	100.00	Using index
 1	SIMPLE	t4	NULL	ALL	NULL	NULL	NULL	NULL	0	0.00	Using where
 Warnings:
-Note	1003	/* select#1 */ select 1 AS `1` from `test`.`t2` left join (`test`.`t1` join `test`.`t3` left join `test`.`t4` on(1)) on((1 and (`test`.`t1`.`a` = `test`.`t3`.`pk`))) where 1
+Note	1003	/* select#1 */ select 1 AS `1` from `test`.`t2` left join (`test`.`t1` join `test`.`t3` left join `test`.`t4` on(1)) on(((`test`.`t3`.`pk` = `test`.`t1`.`a`) and 1)) where 1
 SELECT 1
 FROM t2 LEFT JOIN
 ((t1 JOIN t3 ON t1.a = t3.pk)
@@ -2161,7 +2161,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	t3	NULL	ALL	PRIMARY	NULL	NULL	NULL	1	100.00	Using where; Using join buffer (Block Nested Loop)
 1	SIMPLE	t4	NULL	index	carrier_id	carrier_id	5	NULL	2	100.00	Using where; Using index; Using join buffer (Block Nested Loop)
 Warnings:
-Note	1003	/* select#1 */ select count(0) AS `COUNT(*)` from `test`.`t2` join `test`.`t1` left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t3`.`carrier` = `test`.`t1`.`carrier`) and (`test`.`t3`.`id` = `test`.`t4`.`carrier_id`))) where 1
+Note	1003	/* select#1 */ select count(0) AS `COUNT(*)` from `test`.`t2` join `test`.`t1` left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t4`.`carrier_id` = `test`.`t3`.`id`) and (`test`.`t3`.`carrier` = `test`.`t1`.`carrier`))) where 1
 
 DROP TABLE t1,t2,t3,t4;
 #
@@ -2562,7 +2562,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	t1	NULL	index	col_int_key,col_varchar_key	col_varchar_key	7	NULL	3	100.00	Using index; Using temporary; Using filesort
 1	SIMPLE	t2	NULL	ref	col_varchar_key	col_varchar_key	3	test.t1.col_varchar_key	1	100.00	Using join buffer (Batched Key Access)
 Warnings:
-Note	1003	/* select#1 */ select min(`test`.`t2`.`col_datetime_key`) AS `field1`,`test`.`t1`.`col_int_key` AS `field2` from `test`.`t1` left join `test`.`t2` FORCE INDEX (`col_varchar_key`) on((`test`.`t1`.`col_varchar_key` = `test`.`t2`.`col_varchar_key`)) where 1 group by `field2` order by `field1`
+Note	1003	/* select#1 */ select min(`test`.`t2`.`col_datetime_key`) AS `field1`,`test`.`t1`.`col_int_key` AS `field2` from `test`.`t1` left join `test`.`t2` FORCE INDEX (`col_varchar_key`) on((`test`.`t2`.`col_varchar_key` = `test`.`t1`.`col_varchar_key`)) where 1 group by `field2` order by `field1`
 SELECT MIN(t2.col_datetime_key) AS field1,
 t1.col_int_key AS field2  
 FROM t1
@@ -2622,7 +2622,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	t2	NULL	ALL	NULL	NULL	NULL	NULL	20	100.00	Using temporary; Using filesort
 1	SIMPLE	t1	NULL	ref	col_int_key	col_int_key	4	test.t2.pk	2	100.00	Using join buffer (Batched Key Access)
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t2`.`col_varchar_key` AS `field1`,count(distinct `test`.`t1`.`col_varchar_nokey`) AS `COUNT(DISTINCT t1.col_varchar_nokey)`,`test`.`t2`.`pk` AS `field4` from `test`.`t2` left join `test`.`t1` on((`test`.`t2`.`pk` = `test`.`t1`.`col_int_key`)) where 1 group by `field1`,`field4` order by `test`.`t1`.`col_datetime_key`
+Note	1003	/* select#1 */ select `test`.`t2`.`col_varchar_key` AS `field1`,count(distinct `test`.`t1`.`col_varchar_nokey`) AS `COUNT(DISTINCT t1.col_varchar_nokey)`,`test`.`t2`.`pk` AS `field4` from `test`.`t2` left join `test`.`t1` on((`test`.`t1`.`col_int_key` = `test`.`t2`.`pk`)) where 1 group by `field1`,`field4` order by `test`.`t1`.`col_datetime_key`
 SELECT t2.col_varchar_key AS field1 , COUNT(DISTINCT t1.col_varchar_nokey), t2.pk AS field4
 FROM t1
 RIGHT JOIN t2 ON t2.pk = t1.col_int_key 
@@ -2728,7 +2728,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered
 1	SIMPLE	t3	NULL	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using join buffer (Block Nested Loop)
 1	SIMPLE	t4	NULL	eq_ref	PRIMARY	PRIMARY	4	test.t2.pk	1	100.00	Using join buffer (Batched Key Access)
 Warnings:
-Note	1003	/* select#1 */ select `test`.`t2`.`pk` AS `t2_pk`,`test`.`t4`.`pk` AS `t4_pk`,`test`.`t4`.`k` AS `t4_k`,`test`.`t4`.`i` AS `t4_i` from `test`.`t1` left join `test`.`t2` on((`test`.`t1`.`k` = `test`.`t2`.`pk`)) left join `test`.`t3` on(`test`.`t3`.`i`) left join `test`.`t4` on((`test`.`t4`.`pk` = `test`.`t2`.`pk`)) where 1
+Note	1003	/* select#1 */ select `test`.`t2`.`pk` AS `t2_pk`,`test`.`t4`.`pk` AS `t4_pk`,`test`.`t4`.`k` AS `t4_k`,`test`.`t4`.`i` AS `t4_i` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`pk` = `test`.`t1`.`k`)) left join `test`.`t3` on(`test`.`t3`.`i`) left join `test`.`t4` on((`test`.`t4`.`pk` = `test`.`t2`.`pk`)) where 1
 SELECT t2.pk as t2_pk, t4.pk as t4_pk, t4.k as t4_k, t4.i
 as t4_i FROM t1
 LEFT JOIN t2 ON t1.k = t2.pk