BUG#35850 "Performance regression in 5.1.23/5.1.24"

- Disable the "prefer full scan on clustered primary key over full scan
  of any secondary key" rule introduced by BUG#35850.
- Update test results accordingly 
(bk trigger: file this for BUG#35850)


mysql-test/r/innodb.result:
  BUG#35850 "Performance regression in 5.1.23/5.1.24"
  - Update test results
mysql-test/r/innodb_mysql.result:
  BUG#35850 "Performance regression in 5.1.23/5.1.24"
  - Testcase
  - Update test results
mysql-test/r/join_outer_innodb.result:
  BUG#35850 "Performance regression in 5.1.23/5.1.24"
  - Update test results
mysql-test/t/innodb_mysql.test:
  BUG#35850 "Performance regression in 5.1.23/5.1.24"
  - Testcase
sql/sql_select.cc:
  BUG#35850 "Performance regression in 5.1.23/5.1.24"
  - Disable the "prefer full scan on clustered primary key over full scan
    of any secondary key" rule introduced by BUG#35850.

1 files changed, 18 insertions, 8 deletions

diff --git a/mysql-test/r/innodb_mysql.result b/mysql-test/r/innodb_mysql.result
index 8008fd50a90..ab279933853 100644
--- a/mysql-test/r/innodb_mysql.result
+++ b/mysql-test/r/innodb_mysql.result
@@ -355,13 +355,13 @@ EXPLAIN
 SELECT COUNT(*) FROM t2 LEFT JOIN t1 ON t2.fkey = t1.id
 WHERE t1.name LIKE 'A%';
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	PRIMARY,name	PRIMARY	4	NULL	3	Using where
+1	SIMPLE	t1	index	PRIMARY,name	name	23	NULL	3	Using where; Using index
 1	SIMPLE	t2	ref	fkey	fkey	5	test.t1.id	1	Using where; Using index
 EXPLAIN
 SELECT COUNT(*) FROM t2 LEFT JOIN t1 ON t2.fkey = t1.id
 WHERE t1.name LIKE 'A%' OR FALSE;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	index	NULL	PRIMARY	4	NULL	5	
+1	SIMPLE	t2	index	NULL	fkey	5	NULL	5	Using index
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.fkey	1	Using where
 DROP TABLE t1,t2;
 CREATE TABLE t1 (
@@ -1268,11 +1268,11 @@ select_type	SIMPLE
 table	t1
 type	index
 possible_keys	NULL
-key	PRIMARY
-key_len	4
+key	b
+key_len	5
 ref	NULL
 rows	3
-Extra	Using filesort
+Extra	Using index; Using filesort
 SELECT * FROM t1 ORDER BY b ASC, a DESC;
 a	b
 1	1
@@ -1284,11 +1284,11 @@ select_type	SIMPLE
 table	t1
 type	index
 possible_keys	NULL
-key	PRIMARY
-key_len	4
+key	b
+key_len	5
 ref	NULL
 rows	3
-Extra	Using filesort
+Extra	Using index; Using filesort
 SELECT * FROM t1 ORDER BY b DESC, a ASC;
 a	b
 2	2
@@ -1654,3 +1654,13 @@ ALTER TABLE t1 CHANGE id id2 INT;
 DROP TABLE t2;
 DROP TABLE t1;
 End of 5.1 tests
+drop table if exists t1, t2, t3;
+create table t1(a int);
+insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+create table t2 (a int, b int, pk int, key(a,b), primary key(pk)) engine=innodb;
+insert into t2 select @a:=A.a+10*(B.a + 10*C.a),@a, @a from t1 A, t1 B, t1 C;
+this must use key 'a', not PRIMARY:
+explain select a from t2 where a=b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t2	index	NULL	a	10	NULL	#	Using where; Using index
+drop table t1, t2;