Fix for BUG#8441: in index_merge code when creating index search tuples use

 KEY_PART_INFO::store_length, not KEY_PART_INFO::length (like range code does)

mysql-test/r/index_merge_innodb.result

@@ -123,3 +123,14 @@ key1a = 2 and key1b is null and key3a = 2 and key3b is null;
 count(*)
 4
 drop table t1,t2;
+create table t1 (
+id1 int,
+id2 date ,
+index idx2 (id1,id2),
+index idx1 (id2)  
+) engine = innodb;
+insert into t1 values(1,'20040101'), (2,'20040102');
+select * from t1  where id1 = 1  and id2= '20040101';
+id1	id2
+1	2004-01-01
+drop table t1;

mysql-test/t/index_merge_innodb.test

@@ -120,3 +120,14 @@ select count(*) from t1 where
 
 drop table t1,t2;
 
+# Test for BUG#8441
+create table t1 (
+  id1 int,
+  id2 date ,
+  index idx2 (id1,id2),
+  index idx1 (id2)  
+) engine = innodb;
+insert into t1 values(1,'20040101'), (2,'20040102');
+select * from t1  where id1 = 1  and id2= '20040101'; 
+drop table t1;
+

sql/opt_range.cc

@@ -2593,12 +2593,12 @@ static double ror_scan_selectivity(const ROR_INTERSECT_INFO *info,
       {
         tuple_arg= scan->sel_arg;
         /* Here we use the length of the first key part */
-        tuple_arg->store_min(key_part->length, &key_ptr, 0);
+        tuple_arg->store_min(key_part->store_length, &key_ptr, 0);
       }
       while (tuple_arg->next_key_part != sel_arg)
       {
         tuple_arg= tuple_arg->next_key_part;
-        tuple_arg->store_min(key_part[tuple_arg->part].length, &key_ptr, 0);
+        tuple_arg->store_min(key_part[tuple_arg->part].store_length, &key_ptr, 0);
       }
       min_range.length= max_range.length= ((char*) key_ptr - (char*) key_val);
       records= (info->param->table->file->