Bug#27634: group_by test fails

On many architectures, e.g. 68000, x86, the double registers have higher precision 
than the IEEE standard prescribes. When compiled with flags -O and higher, some double's 
go into registers and therefore have higher precision. In one test case the cost 
information of the best and second-best key were close enough to be influenced by this 
effect, causing a failed test in distribution builds.

Fixed by removing some rows from the table in question so that cost information is not
influenced by decimals beyond standard definition of double.


mysql-test/r/group_by.result:
  Bug#27634: Altered test reslut. The only difference in the results is in the 'rows' column.
mysql-test/t/group_by.test:
  Bug#27634: Altered test case to avoid the corner case where excess precision causes 
  non-minimum costs to appear minimal.

mysql-test/r/group_by.result

@@ -1055,47 +1055,47 @@ INSERT INTO t1 SELECT a + 8,b FROM t1;
 INSERT INTO t1 SELECT a + 16,b FROM t1;
 INSERT INTO t1 SELECT a + 32,b FROM t1;
 INSERT INTO t1 SELECT a + 64,b FROM t1;
-INSERT INTO t1 SELECT a + 128,b FROM t1;
+INSERT INTO t1 SELECT a + 128,b FROM t1 limit 16;
 ANALYZE TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	analyze	status	OK
 EXPLAIN SELECT a FROM t1 WHERE a < 2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY,i2	PRIMARY	4	NULL	2	Using where; Using index
+1	SIMPLE	t1	range	PRIMARY,i2	PRIMARY	4	NULL	1	Using where; Using index
 EXPLAIN SELECT a FROM t1 WHERE a < 2 ORDER BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY,i2	PRIMARY	4	NULL	2	Using where; Using index
+1	SIMPLE	t1	range	PRIMARY,i2	PRIMARY	4	NULL	1	Using where; Using index
 EXPLAIN SELECT a FROM t1 WHERE a < 2 GROUP BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY,i2	PRIMARY	4	NULL	2	Using where; Using index
+1	SIMPLE	t1	range	PRIMARY,i2	PRIMARY	4	NULL	1	Using where; Using index
 EXPLAIN SELECT a FROM t1 IGNORE INDEX (PRIMARY,i2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	256	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	144	
 EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR JOIN (PRIMARY,i2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	256	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	144	
 EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR GROUP BY (PRIMARY,i2) GROUP BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	256	Using index
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	144	Using index
 EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY,i2) ORDER BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	256	Using index; Using filesort
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	144	Using index; Using filesort
 EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY)
 IGNORE INDEX FOR GROUP BY (i2) GROUP BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	256	Using index
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	144	Using index
 EXPLAIN SELECT a FROM t1 IGNORE INDEX (PRIMARY) IGNORE INDEX FOR ORDER BY (i2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	i2	9	NULL	256	Using index
+1	SIMPLE	t1	index	NULL	i2	9	NULL	144	Using index
 EXPLAIN SELECT a FROM t1 FORCE INDEX (i2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	i2	9	NULL	256	Using index
+1	SIMPLE	t1	index	NULL	i2	9	NULL	144	Using index
 EXPLAIN SELECT a FROM t1 USE INDEX ();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	256	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	144	
 EXPLAIN SELECT a FROM t1 USE INDEX () USE INDEX (i2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	256	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	144	
 EXPLAIN SELECT a FROM t1 
 FORCE INDEX (PRIMARY) 
 IGNORE INDEX FOR GROUP BY (i2)
@@ -1104,7 +1104,7 @@ USE INDEX (i2);
 ERROR HY000: Incorrect usage of USE INDEX and FORCE INDEX
 EXPLAIN SELECT a FROM t1 USE INDEX (i2) USE INDEX ();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	i2	9	NULL	256	Using index
+1	SIMPLE	t1	index	NULL	i2	9	NULL	144	Using index
 EXPLAIN SELECT a FROM t1 FORCE INDEX ();
 ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1
 EXPLAIN SELECT a FROM t1 IGNORE INDEX ();
@@ -1112,34 +1112,34 @@ ERROR 42000: You have an error in your SQL syntax; check the manual that corresp
 EXPLAIN SELECT a FROM t1 USE INDEX FOR JOIN (i2) 
 USE INDEX FOR GROUP BY (i2) GROUP BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	i2	9	NULL	256	Using index
+1	SIMPLE	t1	index	NULL	i2	9	NULL	144	Using index
 EXPLAIN SELECT a FROM t1 FORCE INDEX FOR JOIN (i2) 
 FORCE INDEX FOR GROUP BY (i2) GROUP BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	NULL	i2	4	NULL	257	Using index for group-by
+1	SIMPLE	t1	range	NULL	i2	4	NULL	145	Using index for group-by
 EXPLAIN SELECT a FROM t1 USE INDEX () IGNORE INDEX (i2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	256	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	144	
 EXPLAIN SELECT a FROM t1 IGNORE INDEX (i2) USE INDEX ();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	256	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	144	
 EXPLAIN SELECT a FROM t1 
 USE INDEX FOR GROUP BY (i2) 
 USE INDEX FOR ORDER BY (i2)
 USE INDEX FOR JOIN (i2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	i2	9	NULL	256	Using index
+1	SIMPLE	t1	index	NULL	i2	9	NULL	144	Using index
 EXPLAIN SELECT a FROM t1 
 USE INDEX FOR JOIN (i2) 
 USE INDEX FOR JOIN (i2) 
 USE INDEX FOR JOIN (i2,i2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	i2	9	NULL	256	Using index
+1	SIMPLE	t1	index	NULL	i2	9	NULL	144	Using index
 EXPLAIN SELECT 1 FROM t1 WHERE a IN
 (SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	index	NULL	PRIMARY	4	NULL	256	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	256	Using where
+1	PRIMARY	t1	index	NULL	PRIMARY	4	NULL	144	Using where; Using index
+2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	144	Using where
 CREATE TABLE t2 (a INT, b INT, KEY(a));
 INSERT INTO t2 VALUES (1, 1), (2, 2), (3,3), (4,4);
 EXPLAIN SELECT a, SUM(b) FROM t2 GROUP BY a LIMIT 2;
@@ -1152,7 +1152,7 @@ EXPLAIN SELECT 1 FROM t2 WHERE a IN
 (SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	256	Using where
+2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	144	Using where
 SHOW VARIABLES LIKE 'old';
 Variable_name	Value
 old	OFF

mysql-test/t/group_by.test

@@ -780,7 +780,7 @@ INSERT INTO t1 SELECT a + 8,b FROM t1;
 INSERT INTO t1 SELECT a + 16,b FROM t1;
 INSERT INTO t1 SELECT a + 32,b FROM t1;
 INSERT INTO t1 SELECT a + 64,b FROM t1;
-INSERT INTO t1 SELECT a + 128,b FROM t1;
+INSERT INTO t1 SELECT a + 128,b FROM t1 limit 16;
 ANALYZE TABLE t1;
 EXPLAIN SELECT a FROM t1 WHERE a < 2;
 EXPLAIN SELECT a FROM t1 WHERE a < 2 ORDER BY a;