Merge mysql.com:/home/timka/mysql/src/5.0-virgin

into mysql.com:/home/timka/mysql/src/5.0-bug-8532

mysql-test/r/group_min_max.result

@@ -1657,6 +1657,44 @@ a
 b
 c
 d
+select distinct a1,a1 from t1;
+a1	a1
+a	a
+b	b
+c	c
+d	d
+select distinct a2,a1,a2,a1 from t1;
+a2	a1	a2	a1
+a	a	a	a
+b	a	b	a
+a	b	a	b
+b	b	b	b
+a	c	a	c
+b	c	b	c
+a	d	a	d
+b	d	b	d
+select distinct t1.a1,t2.a1 from t1,t2;
+a1	a1
+a	a
+b	a
+c	a
+d	a
+a	b
+b	b
+c	b
+d	b
+a	c
+b	c
+c	c
+d	c
+a	d
+b	d
+c	d
+d	d
+a	e
+b	e
+c	e
+d	e
 explain select distinct a1,a2,b from t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	NULL	idx_t1_1	147	NULL	17	Using index for group-by

mysql-test/t/group_min_max.test

@@ -475,11 +475,15 @@ select distinct a1,a2,b,c from t2 where (a2 >= 'b') and (b = 'a') and (c = 'i121
 select distinct a1,a2,b from t2 where (a1 > 'a') and (a2 > 'a') and (b = 'c');
 select distinct b from t2 where (a2 >= 'b') and (b = 'a');
 
--- BUG 6303
+-- BUG #6303
 select distinct t_00.a1
 from t1 t_00
 where exists ( select * from t2 where a1 = t_00.a1 );
 
+-- BUG #8532 - SELECT DISTINCT a, a causes server to crash
+select distinct a1,a1 from t1;
+select distinct a2,a1,a2,a1 from t1;
+select distinct t1.a1,t2.a1 from t1,t2;
 
 --
 -- DISTINCT queries with GROUP-BY

sql/opt_range.cc

@@ -6878,6 +6878,7 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree)
   SEL_ARG *cur_index_tree= NULL;
   ha_rows cur_quick_prefix_records= 0;
   uint cur_param_idx;
+  key_map cur_used_key_parts;
 
   for (uint cur_index= 0 ; cur_index_info != cur_index_info_end ;
        cur_index_info++, cur_index++)
@@ -6925,17 +6926,25 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree)
     else if (join->select_distinct)
     {
       select_items_it.rewind();
+      cur_used_key_parts.clear_all();
       while ((item= select_items_it++))
       {
         item_field= (Item_field*) item; /* (SA5) already checked above. */
         /* Find the order of the key part in the index. */
         key_part_nr= get_field_keypart(cur_index_info, item_field->field);
+        /*
+          Check if this attribute was already present in the select list.
+          If it was present, then its corresponding key part was alredy used.
+        */
+        if (cur_used_key_parts.is_set(key_part_nr))
+          continue;
         if (key_part_nr < 1 || key_part_nr > join->fields_list.elements)
           goto next_index;
         cur_part= cur_index_info->key_part + key_part_nr - 1;
         cur_group_prefix_len+= cur_part->store_length;
+        cur_used_key_parts.set_bit(key_part_nr);
+        ++cur_group_key_parts;
       }
-      cur_group_key_parts= join->fields_list.elements;
     }
     else
       DBUG_ASSERT(FALSE);