Fix order_by test failure: don't run EXPLAIN for a query that has multiple

range plans with identical costs.

mysql-test/r/order_by.result

@@ -607,9 +607,14 @@ FieldKey	LongVal	StringVal
 1	0	2
 1	1	3
 1	2	1
-EXPLAIN SELECT * FROM t1 WHERE FieldKey > '2' ORDER BY LongVal;
+DS-MRR: use two IGNORE INDEX queries, otherwise we get cost races, because
+DS-MRR: records_in_range/read_time return the same numbers for all three indexes
+EXPLAIN SELECT * FROM t1 IGNORE INDEX (LongField, StringField) WHERE FieldKey > '2' ORDER BY LongVal;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	FieldKey,LongField,StringField	FieldKey	38	NULL	4	Using index condition; Using where; Using MRR; Using filesort
+1	SIMPLE	t1	range	FieldKey	FieldKey	38	NULL	4	Using index condition; Using MRR; Using filesort
+EXPLAIN SELECT * FROM t1 IGNORE INDEX (FieldKey, LongField) WHERE FieldKey > '2' ORDER BY LongVal;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	StringField	StringField	38	NULL	4	Using where; Using filesort
 SELECT * FROM t1 WHERE FieldKey > '2' ORDER BY LongVal;
 FieldKey	LongVal	StringVal
 3	1	2

mysql-test/t/order_by.test

@@ -402,7 +402,11 @@ CREATE TABLE t1 (
 INSERT INTO t1 VALUES ('0',3,'0'),('0',2,'1'),('0',1,'2'),('1',2,'1'),('1',1,'3'), ('1',0,'2'),('2',3,'0'),('2',2,'1'),('2',1,'2'),('2',3,'0'),('2',2,'1'),('2',1,'2'),('3',2,'1'),('3',1,'2'),('3','3','3');
 EXPLAIN SELECT * FROM t1 WHERE FieldKey = '1' ORDER BY LongVal;
 SELECT * FROM t1 WHERE FieldKey = '1' ORDER BY LongVal;
-EXPLAIN SELECT * FROM t1 WHERE FieldKey > '2' ORDER BY LongVal;
+--echo DS-MRR: use two IGNORE INDEX queries, otherwise we get cost races, because
+--echo DS-MRR: records_in_range/read_time return the same numbers for all three indexes
+EXPLAIN SELECT * FROM t1 IGNORE INDEX (LongField, StringField) WHERE FieldKey > '2' ORDER BY LongVal;
+EXPLAIN SELECT * FROM t1 IGNORE INDEX (FieldKey, LongField) WHERE FieldKey > '2' ORDER BY LongVal;
+
 SELECT * FROM t1 WHERE FieldKey > '2' ORDER BY LongVal;
 EXPLAIN SELECT * FROM t1 WHERE FieldKey > '2' ORDER BY FieldKey, LongVal;
 SELECT * FROM t1 WHERE FieldKey > '2' ORDER BY FieldKey, LongVal;