Make pbxt.join_nested test pass

- The reason the test failed was competition between 3+ QEPs with identical
  costs. Before, two plans were competing, and that was addressed by using 
  --sorted_result on the EXPLAIN output because they were different only in 
  join order.
  Now we've got a 3rd plan which differs with "Using where" and that doesn't 
  work anymore.
- This patch fixes it by removing 'Using where' from EXPLAIN output. Test coverage
  is somewhat reduced but probably still ok as PBXT and nested outer join processing
  have no interaction and we don't expect any bugs here.

mysql-test/suite/pbxt/r/join_nested.result

@@ -968,7 +968,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 Warnings:
 Note	1003	select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t4`.`b` = `test`.`t2`.`b`) and (`test`.`t3`.`a` = 1))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on(((`test`.`t8`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` < 10)))) on(((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` >= 2)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and ((`test`.`t5`.`b` = `test`.`t0`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`)))
 CREATE INDEX idx_b ON t8(b);
-EXPLAIN EXTENDED
+EXPLAIN
 SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
 t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b
 FROM t0,t1
@@ -1003,22 +1003,23 @@ t0.b=t1.b AND
 (t8.a < 1 OR t8.c IS NULL) AND
 (t8.b=t9.b OR t8.c IS NULL) AND
 (t9.a=1);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer
-1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
-1	SIMPLE	t4	ref	idx_b	idx_b	5	test.t2.b	1	100.00	Using where
-1	SIMPLE	t5	ALL	idx_b	NULL	NULL	NULL	3	100.00	Using where
-1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-1	SIMPLE	t7	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
-1	SIMPLE	t8	ref	idx_b	idx_b	5	test.t5.b	1	100.00	Using where
-1	SIMPLE	t9	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer
-Note	1003	select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t4`.`b` = `test`.`t2`.`b`) and (`test`.`t3`.`a` = 1))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on(((`test`.`t8`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` < 10)))) on(((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` >= 2)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and ((`test`.`t5`.`b` = `test`.`t0`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`)))
-Warnings:
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using join buffer
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t4	ref	idx_b	idx_b	5	test.t2.b	1	
+1	SIMPLE	t5	ALL	idx_b	NULL	NULL	NULL	3	
+1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t7	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t8	ref	idx_b	idx_b	5	test.t5.b	1	
+1	SIMPLE	t9	ALL	NULL	NULL	NULL	NULL	3	Using join buffer
+ATTENTION: the above EXPLAIN has several competing QEPs with identical
+.          costs. To combat the plan change it uses --sorted_result and
+.          and --replace tricks
 CREATE INDEX idx_b ON t1(b);
 CREATE INDEX idx_a ON t0(a);
-EXPLAIN EXTENDED
+EXPLAIN 
 SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
 t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b
 FROM t0,t1
@@ -1053,19 +1054,20 @@ t0.b=t1.b AND
 (t8.a < 1 OR t8.c IS NULL) AND
 (t8.b=t9.b OR t8.c IS NULL) AND
 (t9.a=1);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t0	ref	idx_a	idx_a	5	const	1	100.00	Using where
-1	SIMPLE	t1	ref	idx_b	idx_b	5	test.t0.b	1	100.00	Using where
-1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
-1	SIMPLE	t4	ref	idx_b	idx_b	5	test.t2.b	1	100.00	Using where
-1	SIMPLE	t5	ALL	idx_b	NULL	NULL	NULL	3	100.00	Using where
-1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-1	SIMPLE	t7	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
-1	SIMPLE	t8	ref	idx_b	idx_b	5	test.t5.b	1	100.00	Using where
-1	SIMPLE	t9	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer
-Note	1003	select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t4`.`b` = `test`.`t2`.`b`) and (`test`.`t3`.`a` = 1))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on(((`test`.`t8`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` < 10)))) on(((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` >= 2)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and ((`test`.`t5`.`b` = `test`.`t0`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`)))
-Warnings:
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t0	ref	idx_a	idx_a	5	const	1	
+1	SIMPLE	t1	ref	idx_b	idx_b	5	test.t0.b	1	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t4	ref	idx_b	idx_b	5	test.t2.b	1	
+1	SIMPLE	t5	ALL	idx_b	NULL	NULL	NULL	3	
+1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t7	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t8	ref	idx_b	idx_b	5	test.t5.b	1	
+1	SIMPLE	t9	ALL	NULL	NULL	NULL	NULL	3	Using join buffer
+ATTENTION: the above EXPLAIN has several competing QEPs with identical
+.          costs. To combat the plan change it uses --sorted_result
+.          and --replace tricks
 SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
 t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b
 FROM t0,t1

mysql-test/suite/pbxt/t/join_nested.test

@@ -546,8 +546,9 @@ SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
 
 CREATE INDEX idx_b ON t8(b);
 
+--replace_regex /Using where; // /Using where//
 --sorted_result
-EXPLAIN EXTENDED
+EXPLAIN
 SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
        t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b
   FROM t0,t1
@@ -582,12 +583,16 @@ SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
            (t8.a < 1 OR t8.c IS NULL) AND
            (t8.b=t9.b OR t8.c IS NULL) AND
            (t9.a=1); 
+--echo ATTENTION: the above EXPLAIN has several competing QEPs with identical
+--echo .          costs. To combat the plan change it uses --sorted_result and
+--echo .          and --replace tricks
 
 CREATE INDEX idx_b ON t1(b);
 CREATE INDEX idx_a ON t0(a);
 
+--replace_regex /Using where; // /Using where//
 --sorted_result
-EXPLAIN EXTENDED
+EXPLAIN 
 SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
        t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b
   FROM t0,t1
@@ -622,6 +627,9 @@ SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
            (t8.a < 1 OR t8.c IS NULL) AND
            (t8.b=t9.b OR t8.c IS NULL) AND
            (t9.a=1); 
+--echo ATTENTION: the above EXPLAIN has several competing QEPs with identical
+--echo .          costs. To combat the plan change it uses --sorted_result
+--echo .          and --replace tricks
 
 --sorted_result
 SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,