Merge mysql.com:/home/kgeorge/mysql/4.1/B4981

into  mysql.com:/home/kgeorge/mysql/5.0/B4981

mysql-test/r/select.result

@@ -3446,3 +3446,17 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	PRIMARY,b	b	5	NULL	3	Using where
 1	SIMPLE	t2	ref	c	c	5	test.t1.a	2	Using where
 DROP TABLE t1, t2;
+CREATE TABLE t1(a int, b int, c int, KEY b(b), KEY c(c));
+insert into t1 values (1,0,0),(2,0,0);
+CREATE TABLE t2 (a int, b varchar(2), c varchar(2), PRIMARY KEY(a));
+insert into t2 values (1,'',''), (2,'','');
+CREATE TABLE t3 (a int, b int, PRIMARY KEY (a,b), KEY a (a), KEY b (b));
+insert into t3 values (1,1),(1,2);
+explain select straight_join DISTINCT t2.a,t2.b, t1.c from t1, t3, t2 
+where (t1.c=t2.a or (t1.c=t3.a and t2.a=t3.b)) and t1.b=556476786 and 
+t2.b like '%%' order by t2.b limit 0,1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ref	b,c	b	5	const	1	Using where; Using temporary; Using filesort
+1	SIMPLE	t3	index	PRIMARY,a,b	PRIMARY	8	NULL	2	Using index
+1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	2	Range checked for each record (index map: 0x1)
+DROP TABLE t1,t2,t3;

mysql-test/t/select.test

@@ -2264,6 +2264,20 @@ insert into t2 values(1,1);
 select * from t1 where f1 in (select f3 from t2 where (f3,f4)= (select f3,f4 from t2)); 
 drop table t1,t2;
 
+#
+# Bug #4981: 4.x and 5.x produce non-optimal execution path, 3.23 regression test failure
+#
+CREATE TABLE t1(a int, b int, c int, KEY b(b), KEY c(c));
+insert into t1 values (1,0,0),(2,0,0);
+CREATE TABLE t2 (a int, b varchar(2), c varchar(2), PRIMARY KEY(a));
+insert into t2 values (1,'',''), (2,'','');
+CREATE TABLE t3 (a int, b int, PRIMARY KEY (a,b), KEY a (a), KEY b (b));
+insert into t3 values (1,1),(1,2);
+# must have "range checked" for t2
+explain select straight_join DISTINCT t2.a,t2.b, t1.c from t1, t3, t2 
+ where (t1.c=t2.a or (t1.c=t3.a and t2.a=t3.b)) and t1.b=556476786 and 
+       t2.b like '%%' order by t2.b limit 0,1;
+DROP TABLE t1,t2,t3;
 # End of 4.1 tests
 
 #

sql/opt_range.cc

@@ -81,7 +81,7 @@ public:
 	  uint8 min_flag, uint8 max_flag, uint8 maybe_flag);
   SEL_ARG(enum Type type_arg)
     :elements(1),use_count(1),left(0),next_key_part(0),color(BLACK),
-     type(type_arg)
+     type(type_arg),min_flag(0)
   {}
   inline bool is_same(SEL_ARG *arg)
   {