Merge olga.mysql.com:/home/igor/mysql-5.0-opt

into  olga.mysql.com:/home/igor/dev-opt/mysql-5.0-opt-bug25602


sql/sql_select.cc:
  Auto merged

mysql-test/r/group_min_max.result

@@ -2286,3 +2286,24 @@ Variable_name	Value
 Handler_read_key	8
 Handler_read_next	1
 DROP TABLE t1,t2,t3;
+CREATE TABLE t1 (a int, INDEX idx(a));
+INSERT INTO t1 VALUES
+(4), (2), (1), (2), (4), (2), (1), (4),
+(4), (2), (1), (2), (2), (4), (1), (4);
+EXPLAIN SELECT DISTINCT(a) FROM t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	NULL	idx	5	NULL	9	Using index for group-by
+SELECT DISTINCT(a) FROM t1;
+a
+1
+2
+4
+EXPLAIN SELECT SQL_BIG_RESULT DISTINCT(a) FROM t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	NULL	idx	5	NULL	9	Using index for group-by
+SELECT SQL_BIG_RESULT DISTINCT(a) FROM t1;
+a
+1
+2
+4
+DROP TABLE t1;

mysql-test/t/group_min_max.test

@@ -870,3 +870,25 @@ DELETE FROM t3 WHERE (SELECT (SELECT MAX(b) FROM t1 GROUP BY a HAVING a < 2) x
 SHOW STATUS LIKE 'handler_read__e%';
 
 DROP TABLE t1,t2,t3;
+
+#
+# Bug#25602: queries with DISTINCT and SQL_BIG_RESULT hint 
+#            for which loose scan optimization is applied
+#
+
+CREATE TABLE t1 (a int, INDEX idx(a));
+INSERT INTO t1 VALUES
+  (4), (2), (1), (2), (4), (2), (1), (4),
+  (4), (2), (1), (2), (2), (4), (1), (4);
+
+EXPLAIN SELECT DISTINCT(a) FROM t1;
+SELECT DISTINCT(a) FROM t1;
+EXPLAIN SELECT SQL_BIG_RESULT DISTINCT(a) FROM t1;
+SELECT SQL_BIG_RESULT DISTINCT(a) FROM t1;
+
+DROP TABLE t1;
+
+
+
+
+

sql/sql_select.cc

@@ -12551,10 +12551,14 @@ create_sort_index(THD *thd, JOIN *join, ORDER *order,
 
   /*
     When there is SQL_BIG_RESULT do not sort using index for GROUP BY,
-    and thus force sorting on disk.
+    and thus force sorting on disk unless a group min-max optimization
+    is going to be used as it is applied now only for one table queries
+    with covering indexes.
   */
   if ((order != join->group_list || 
-       !(join->select_options & SELECT_BIG_RESULT)) &&
+       !(join->select_options & SELECT_BIG_RESULT) ||
+       select && select->quick &&
+       select->quick->get_type() == QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX) &&
       test_if_skip_sort_order(tab,order,select_limit,0))
     DBUG_RETURN(0);
   for (ORDER *ord= join->order; ord; ord= ord->next)