Only generate BKA plans that maintains sort order

Summary:
If the storage engine supports sorted MRR, and this is not part of an outer join, then BKA will actually always produce ordered results. Outer joins are unordered because the BKA algorithm outputs matching rows first, followed by non-matching rows. It is probably possible to extend `BKAIterator::Read` to always produced sorted rows if sorted MRR is supported, and get rid of the outer join check. The current check also includes antijoins, even though antijoins also produce sorted output.

Because the decision to use BKA is not cost based, and it is always chosen if available, it will sometimes regress plans when NLJ can skip filesort while BKA cannot skip filesort. To fix this, produce BKA only if it produces ordered results, or if there's no order by clause.

If the order by clause does not match the order of the outer table, then technically BKA is still usable, since filesort is needed regardless of BKA/NLJ. This case is not handled here, and NLJ will always be chosen.

Reviewed By: luqun

Differential Revision: D35678857

Author: lth

mysql-test/include/diff_query.inc

@@ -0,0 +1,16 @@
+--disable_query_log
+
+--output $MYSQL_TMP_DIR/A
+--eval $query
+
+--eval $setup
+--output $MYSQL_TMP_DIR/B
+--eval $query
+--eval $restore
+
+--enable_query_log
+
+--diff_files $MYSQL_TMP_DIR/A $MYSQL_TMP_DIR/B
+
+--remove_file $MYSQL_TMP_DIR/A
+--remove_file $MYSQL_TMP_DIR/B

mysql-test/r/join_cache_bka.result

@@ -1526,8 +1526,8 @@ explain
 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;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	index	PRIMARY	PRIMARY	4	NULL	#	100.00	Using index; Using temporary
-1	SIMPLE	t2	NULL	ref	i_a	i_a	5	test.t1.a	#	100.00	Using where; Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	index	PRIMARY	PRIMARY	4	NULL	#	100.00	Using index
+1	SIMPLE	t2	NULL	ref	i_a	i_a	5	test.t1.a	#	100.00	Using where
 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`.`t2`.`a` = `test`.`t1`.`a`) and ((`test`.`t2`.`p` % 2) = 1))) where true group by `test`.`t1`.`a`
 select t1.a, count(t2.p) as count
@@ -1888,8 +1888,8 @@ explain
 select t1.id1, sum(t2.id2) from t1 join t2 on t1.id1=t2.id1 
 where t1.d=3 group by t1.id1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	ref	idx1	idx1	5	const	4	100.00	Using where; Using index; Using temporary
-1	SIMPLE	t2	NULL	ref	idx2	idx2	5	test.t1.id1	3	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	ref	idx1	idx1	5	const	4	100.00	Using where; Using index
+1	SIMPLE	t2	NULL	ref	idx2	idx2	5	test.t1.id1	3	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`id1` AS `id1`,sum(`test`.`t2`.`id2`) AS `sum(t2.id2)` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`id1` = `test`.`t1`.`id1`) and (`test`.`t1`.`d` = 3)) group by `test`.`t1`.`id1`
 select t1.id1, sum(t2.id2) from t1 join t2 on t1.id1=t2.id1 
@@ -2475,7 +2475,7 @@ ORDER BY t1.col_int_key, t1.col_datetime
 LIMIT 2;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	NULL	ALL	col_int_key	NULL	NULL	NULL	4	100.00	Using temporary; Using filesort
-1	SIMPLE	t2	NULL	ref	col_int_key	col_int_key	5	const	2	50.00	Using where; Using join buffer (Batched Key Access)
+1	SIMPLE	t2	NULL	ref	col_int_key	col_int_key	5	const	2	50.00	Using where
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`col_int_key` AS `col_int_key`,`test`.`t1`.`col_datetime` AS `col_datetime` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`col_int_key` = 1) and (`test`.`t2`.`col_int` >= 3)) group by `test`.`t1`.`col_int_key` order by `test`.`t1`.`col_int_key`,`test`.`t1`.`col_datetime` limit 2
 SELECT t1.col_int_key, t1.col_datetime 
@@ -2778,8 +2778,8 @@ ON t1.col_varchar_key = t2.col_varchar_key
 GROUP BY field2
 ORDER BY field1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	index	col_int_key,col_varchar_key	col_varchar_key	10	NULL	3	100.00	Using index; Using temporary; Using filesort
-1	SIMPLE	t2	NULL	ref	col_varchar_key	col_varchar_key	6	test.t1.col_varchar_key	1	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	index	col_int_key,col_varchar_key	col_int_key	4	NULL	3	100.00	Using temporary; Using filesort
+1	SIMPLE	t2	NULL	ref	col_varchar_key	col_varchar_key	6	test.t1.col_varchar_key	1	100.00	NULL
 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`.`t2`.`col_varchar_key` = `test`.`t1`.`col_varchar_key`)) where true group by `field2` order by `field1`
 SELECT MIN(t2.col_datetime_key) AS field1,
@@ -2847,7 +2847,7 @@ GROUP BY field1 , field4
 ORDER BY t1.col_datetime_key ;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 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	1	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	ref	col_int_key	col_int_key	4	test.t2.pk	1	100.00	NULL
 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`.`t1`.`col_int_key` = `test`.`t2`.`pk`)) where true 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

mysql-test/r/join_cache_bka_nobnl.result

@@ -1526,8 +1526,8 @@ explain
 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;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	index	PRIMARY	PRIMARY	4	NULL	#	100.00	Using index; Using temporary
-1	SIMPLE	t2	NULL	ref	i_a	i_a	5	test.t1.a	#	100.00	Using where; Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	index	PRIMARY	PRIMARY	4	NULL	#	100.00	Using index
+1	SIMPLE	t2	NULL	ref	i_a	i_a	5	test.t1.a	#	100.00	Using where
 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`.`t2`.`a` = `test`.`t1`.`a`) and ((`test`.`t2`.`p` % 2) = 1))) where true group by `test`.`t1`.`a`
 select t1.a, count(t2.p) as count
@@ -1888,8 +1888,8 @@ explain
 select t1.id1, sum(t2.id2) from t1 join t2 on t1.id1=t2.id1 
 where t1.d=3 group by t1.id1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	ref	idx1	idx1	5	const	4	100.00	Using where; Using index; Using temporary
-1	SIMPLE	t2	NULL	ref	idx2	idx2	5	test.t1.id1	3	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	ref	idx1	idx1	5	const	4	100.00	Using where; Using index
+1	SIMPLE	t2	NULL	ref	idx2	idx2	5	test.t1.id1	3	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`id1` AS `id1`,sum(`test`.`t2`.`id2`) AS `sum(t2.id2)` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`id1` = `test`.`t1`.`id1`) and (`test`.`t1`.`d` = 3)) group by `test`.`t1`.`id1`
 select t1.id1, sum(t2.id2) from t1 join t2 on t1.id1=t2.id1 
@@ -1902,8 +1902,8 @@ explain
 select t1.id1  from t1 join t2 on t1.id1=t2.id1 
 where t1.d=3 and t2.id2 > 200 order by t1.id1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	ref	idx1	idx1	5	const	4	100.00	Using where; Using index; Using temporary; Using filesort
-1	SIMPLE	t2	NULL	ref	idx2	idx2	5	test.t1.id1	3	33.33	Using where; Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	ref	idx1	idx1	5	const	4	100.00	Using where; Using index
+1	SIMPLE	t2	NULL	ref	idx2	idx2	5	test.t1.id1	3	33.33	Using where
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`id1` AS `id1` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`id1` = `test`.`t1`.`id1`) and (`test`.`t1`.`d` = 3) and (`test`.`t2`.`id2` > 200)) order by `test`.`t1`.`id1`
 select t1.id1  from t1 join t2 on t1.id1=t2.id1 
@@ -2475,7 +2475,7 @@ ORDER BY t1.col_int_key, t1.col_datetime
 LIMIT 2;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	NULL	ALL	col_int_key	NULL	NULL	NULL	4	100.00	Using temporary; Using filesort
-1	SIMPLE	t2	NULL	ref	col_int_key	col_int_key	5	const	2	50.00	Using where; Using join buffer (Batched Key Access)
+1	SIMPLE	t2	NULL	ref	col_int_key	col_int_key	5	const	2	50.00	Using where
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`col_int_key` AS `col_int_key`,`test`.`t1`.`col_datetime` AS `col_datetime` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`col_int_key` = 1) and (`test`.`t2`.`col_int` >= 3)) group by `test`.`t1`.`col_int_key` order by `test`.`t1`.`col_int_key`,`test`.`t1`.`col_datetime` limit 2
 SELECT t1.col_int_key, t1.col_datetime 
@@ -2778,8 +2778,8 @@ ON t1.col_varchar_key = t2.col_varchar_key
 GROUP BY field2
 ORDER BY field1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	index	col_int_key,col_varchar_key	col_varchar_key	10	NULL	3	100.00	Using index; Using temporary; Using filesort
-1	SIMPLE	t2	NULL	ref	col_varchar_key	col_varchar_key	6	test.t1.col_varchar_key	1	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	index	col_int_key,col_varchar_key	col_int_key	4	NULL	3	100.00	Using temporary; Using filesort
+1	SIMPLE	t2	NULL	ref	col_varchar_key	col_varchar_key	6	test.t1.col_varchar_key	1	100.00	NULL
 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`.`t2`.`col_varchar_key` = `test`.`t1`.`col_varchar_key`)) where true group by `field2` order by `field1`
 SELECT MIN(t2.col_datetime_key) AS field1,
@@ -2847,7 +2847,7 @@ GROUP BY field1 , field4
 ORDER BY t1.col_datetime_key ;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 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	1	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	ref	col_int_key	col_int_key	4	test.t2.pk	1	100.00	NULL
 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`.`t1`.`col_int_key` = `test`.`t2`.`pk`)) where true 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

mysql-test/r/select_all_bka.result

@@ -643,19 +643,19 @@ Note	1003	/* select#1 */ select `test`.`t3`.`t2nr` AS `t2nr`,`test`.`t2`.`fld3`
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t3`.`period` = `test`.`t1`.`period`) order by `test`.`t3`.`period`
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period limit 10;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t3	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t1	NULL	ref	period	period	4	test.t3.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t3	NULL	index	period	period	4	NULL	1	100.00	NULL
+1	SIMPLE	t1	NULL	ref	period	period	4	test.t3.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t1`.`period` = `test`.`t3`.`period`) order by `test`.`t3`.`period` limit 10
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t1.period limit 10;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	index	period	period	4	NULL	1	100.00	NULL
+1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t3`.`period` = `test`.`t1`.`period`) order by `test`.`t1`.`period` limit 10
 select period from t1;

mysql-test/r/select_all_bka_nobnl.result

@@ -643,19 +643,19 @@ Note	1003	/* select#1 */ select `test`.`t3`.`t2nr` AS `t2nr`,`test`.`t2`.`fld3`
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t3`.`period` = `test`.`t1`.`period`) order by `test`.`t3`.`period`
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period limit 10;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t3	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t1	NULL	ref	period	period	4	test.t3.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t3	NULL	index	period	period	4	NULL	1	100.00	NULL
+1	SIMPLE	t1	NULL	ref	period	period	4	test.t3.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t1`.`period` = `test`.`t3`.`period`) order by `test`.`t3`.`period` limit 10
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t1.period limit 10;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	index	period	period	4	NULL	1	100.00	NULL
+1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t3`.`period` = `test`.`t1`.`period`) order by `test`.`t1`.`period` limit 10
 select period from t1;

mysql-test/r/select_icp_mrr_bka.result

@@ -643,19 +643,19 @@ Note	1003	/* select#1 */ select `test`.`t3`.`t2nr` AS `t2nr`,`test`.`t2`.`fld3`
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t3`.`period` = `test`.`t1`.`period`) order by `test`.`t3`.`period`
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period limit 10;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t3	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t1	NULL	ref	period	period	4	test.t3.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t3	NULL	index	period	period	4	NULL	1	100.00	NULL
+1	SIMPLE	t1	NULL	ref	period	period	4	test.t3.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t1`.`period` = `test`.`t3`.`period`) order by `test`.`t3`.`period` limit 10
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t1.period limit 10;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	NULL	ALL	period	NULL	NULL	NULL	41810	100.00	Using temporary; Using filesort
-1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	Using join buffer (Batched Key Access)
+1	SIMPLE	t1	NULL	index	period	period	4	NULL	1	100.00	NULL
+1	SIMPLE	t3	NULL	ref	period	period	4	test.t1.period	4181	100.00	NULL
 Warnings:
 Note	1003	/* select#1 */ select `test`.`t1`.`t2nr` AS `t2nr`,`test`.`t1`.`period` AS `period`,`test`.`t1`.`name` AS `name`,`test`.`t1`.`companynr` AS `companynr`,`test`.`t1`.`price` AS `price`,`test`.`t1`.`price2` AS `price2`,`test`.`t3`.`t2nr` AS `t2nr`,`test`.`t3`.`period` AS `period`,`test`.`t3`.`name` AS `name`,`test`.`t3`.`companynr` AS `companynr`,`test`.`t3`.`price` AS `price`,`test`.`t3`.`price2` AS `price2` from `test`.`t3` `t1` join `test`.`t3` where (`test`.`t3`.`period` = `test`.`t1`.`period`) order by `test`.`t1`.`period` limit 10
 select period from t1;