Fixed bug #28189: in some rare cases optimizer preferred a more expensive

ref access to a less expensive range access. 
This occurred only with InnoDB tables.

mysql-test/r/innodb_mysql.result

@@ -544,4 +544,56 @@ id	c	counter
 3	b	2
 4	a	2
 drop table t1;
+CREATE TABLE t1(
+id int AUTO_INCREMENT PRIMARY KEY,
+stat_id int NOT NULL,
+acct_id int DEFAULT NULL,
+INDEX idx1 (stat_id, acct_id),
+INDEX idx2 (acct_id)
+) ENGINE=MyISAM;
+CREATE TABLE t2(
+id int AUTO_INCREMENT PRIMARY KEY,
+stat_id int NOT NULL,
+acct_id int DEFAULT NULL,
+INDEX idx1 (stat_id, acct_id),
+INDEX idx2 (acct_id)
+) ENGINE=InnoDB;
+INSERT INTO t1(stat_id,acct_id) VALUES
+(1,759), (2,831), (3,785), (4,854), (1,921),
+(1,553), (2,589), (3,743), (2,827), (2,545),
+(4,779), (4,783), (1,597), (1,785), (4,832),
+(1,741), (1,833), (3,788), (2,973), (1,907);
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+UPDATE t1 SET acct_id=785 
+WHERE MOD(stat_id,2)=0 AND MOD(id,stat_id)=MOD(acct_id,stat_id);
+OPTIMIZE TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	optimize	status	OK
+SELECT COUNT(*) FROM t1;
+COUNT(*)
+40960
+SELECT COUNT(*) FROM t1 WHERE acct_id=785;
+COUNT(*)
+8702
+EXPLAIN SELECT COUNT(*) FROM t1 WHERE stat_id IN (1,3) AND acct_id=785;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	idx1,idx2	idx1	9	NULL	2	Using where; Using index
+INSERT INTO t2 SELECT * FROM t1;
+OPTIMIZE TABLE t2;
+Table	Op	Msg_type	Msg_text
+test.t2	optimize	status	OK
+EXPLAIN SELECT COUNT(*) FROM t2 WHERE stat_id IN (1,3) AND acct_id=785;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t2	range	idx1,idx2	idx1	9	NULL	2	Using where; Using index
+DROP TABLE t1,t2;
 End of 5.0 tests

mysql-test/t/innodb_mysql.test

@@ -518,4 +518,58 @@ select * from t1;
 
 drop table t1;
 
+#
+# Bug #28189: optimizer erroniously prefers ref access to range access 
+#             for an InnoDB table
+#
+
+CREATE TABLE t1(
+  id int AUTO_INCREMENT PRIMARY KEY,
+  stat_id int NOT NULL,
+  acct_id int DEFAULT NULL,
+  INDEX idx1 (stat_id, acct_id),
+  INDEX idx2 (acct_id)
+) ENGINE=MyISAM;
+
+CREATE TABLE t2(
+  id int AUTO_INCREMENT PRIMARY KEY,
+  stat_id int NOT NULL,
+  acct_id int DEFAULT NULL,
+  INDEX idx1 (stat_id, acct_id),
+  INDEX idx2 (acct_id)
+) ENGINE=InnoDB;
+
+INSERT INTO t1(stat_id,acct_id) VALUES
+  (1,759), (2,831), (3,785), (4,854), (1,921),
+  (1,553), (2,589), (3,743), (2,827), (2,545),
+  (4,779), (4,783), (1,597), (1,785), (4,832),
+  (1,741), (1,833), (3,788), (2,973), (1,907);
+
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+INSERT INTO t1(stat_id,acct_id) SELECT stat_id, mod(id+100000, acct_id) FROM t1;
+UPDATE t1 SET acct_id=785 
+  WHERE MOD(stat_id,2)=0 AND MOD(id,stat_id)=MOD(acct_id,stat_id);
+OPTIMIZE TABLE t1;
+
+SELECT COUNT(*) FROM t1;
+SELECT COUNT(*) FROM t1 WHERE acct_id=785;
+
+EXPLAIN SELECT COUNT(*) FROM t1 WHERE stat_id IN (1,3) AND acct_id=785; 
+
+INSERT INTO t2 SELECT * FROM t1;
+OPTIMIZE TABLE t2;
+
+EXPLAIN SELECT COUNT(*) FROM t2 WHERE stat_id IN (1,3) AND acct_id=785;
+
+DROP TABLE t1,t2; 
+
 --echo End of 5.0 tests

sql/sql_select.cc

@@ -4189,7 +4189,7 @@ best_access_path(JOIN      *join,
       !(s->quick && best_key && s->quick->index == best_key->key &&      // (2)
         best_max_key_part >= s->table->quick_key_parts[best_key->key]) &&// (2)
       !((s->table->file->table_flags() & HA_TABLE_SCAN_ON_INDEX) &&      // (3)
-        ! s->table->used_keys.is_clear_all() && best_key) &&             // (3)
+        ! s->table->used_keys.is_clear_all() && best_key && !s->quick) &&// (3)
       !(s->table->force_index && best_key && !s->quick))                 // (4)
   {                                             // Check full join
     ha_rows rnd_records= s->found_records;