Backporting of jorgen.loland@sun.com-20100618093212-lifp1psig3hbj6jj

from mysql-next-mr-opt-backporting.

Bug#54515: Crash in opt_range.cc::get_best_group_min_max on 
           SELECT from VIEW with GROUP BY
      
When handling the grouping items in get_best_group_min_max, the
items need to be of type Item_field. In this bug, an ASSERT 
triggered because the item used for grouping was an 
Item_direct_view_ref (i.e., the group column is from a view). 
The fix is to get the real_item since Item_ref* pointing to 
Item_field is ok.

mysql-test/r/select.result

@@ -4857,3 +4857,22 @@ SELECT * FROM t1 WHERE 102 < c;
 a	b	c
 DROP TABLE t1;
 End of 5.1 tests
+#
+# Bug#54515: Crash in opt_range.cc::get_best_group_min_max on 
+#            SELECT from VIEW with GROUP BY
+#
+CREATE TABLE t1 (
+col_int_key int DEFAULT NULL,
+KEY int_key (col_int_key)
+) ;
+INSERT INTO t1 VALUES (1),(2);
+CREATE VIEW view_t1 AS 
+SELECT t1.col_int_key AS col_int_key
+FROM t1;
+SELECT col_int_key FROM view_t1 GROUP BY col_int_key;
+col_int_key
+1
+2
+DROP VIEW view_t1;
+DROP TABLE t1;
+# End of test BUG#54515

mysql-test/t/select.test

@@ -4118,3 +4118,26 @@ DROP TABLE t1;
 
 
 --echo End of 5.1 tests
+
+--echo #
+--echo # Bug#54515: Crash in opt_range.cc::get_best_group_min_max on 
+--echo #            SELECT from VIEW with GROUP BY
+--echo #
+
+CREATE TABLE t1 (
+  col_int_key int DEFAULT NULL,
+  KEY int_key (col_int_key)
+) ;
+
+INSERT INTO t1 VALUES (1),(2);
+
+CREATE VIEW view_t1 AS 
+  SELECT t1.col_int_key AS col_int_key
+  FROM t1;
+
+SELECT col_int_key FROM view_t1 GROUP BY col_int_key;
+
+DROP VIEW view_t1;
+DROP TABLE t1;
+
+--echo # End of test BUG#54515

sql/opt_range.cc

@@ -9570,8 +9570,8 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree, double read_time)
           first Item? If so, then why? What is the array for?
         */
         /* Above we already checked that all group items are fields. */
-        DBUG_ASSERT((*tmp_group->item)->type() == Item::FIELD_ITEM);
-        Item_field *group_field= (Item_field *) (*tmp_group->item);
+        DBUG_ASSERT((*tmp_group->item)->real_item()->type() == Item::FIELD_ITEM);
+        Item_field *group_field= (Item_field *) (*tmp_group->item)->real_item();
         if (group_field->field->eq(cur_part->field))
         {
           cur_group_prefix_len+= cur_part->store_length;