Fixed bug #29104: assertion abort for grouping queries using views.

The abort happened when a query contained a conjunctive predicate
of the form 'view column = constant' in the WHERE condition and 
the grouping list also contained a reference to a view column yet
a different one.

Removed the failing assertion as invalid in a general case.

Also fixed a bug that prevented applying some optimization for grouping
queries using views. If the WHERE condition of such a query contains
a conjunctive condition of the form 'view column = constant' and
this view column is used in the grouping list then grouping by this
column can be eliminated. The bug blocked performing this elimination.

mysql-test/r/view.result

@@ -3476,4 +3476,28 @@ a1	c
 2	0
 DROP VIEW v1,v2;
 DROP TABLE t1,t2,t3,t4;
+CREATE TABLE t1 (a int, b int);
+INSERT INTO t1 VALUES (1,2), (2,2), (1,3), (1,2);
+CREATE VIEW v1 AS SELECT a, b+1 as b FROM t1;
+SELECT b, SUM(a) FROM v1 WHERE b=3 GROUP BY b;
+b	SUM(a)
+3	4
+EXPLAIN SELECT b, SUM(a) FROM v1 WHERE b=3 GROUP BY b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
+SELECT a, SUM(b) FROM v1 WHERE b=3 GROUP BY a;
+a	SUM(b)
+1	6
+2	3
+EXPLAIN SELECT a, SUM(b) FROM v1 WHERE b=3 GROUP BY a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where; Using temporary; Using filesort
+SELECT a, SUM(b) FROM v1 WHERE a=1 GROUP BY a;
+a	SUM(b)
+1	10
+EXPLAIN SELECT a, SUM(b) FROM v1 WHERE a=1 GROUP BY a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
+DROP VIEW v1;
+DROP TABLE t1;
 End of 5.0 tests.

mysql-test/t/view.test

@@ -3324,4 +3324,28 @@ SELECT * FROM t1;
 DROP VIEW v1,v2;
 DROP TABLE t1,t2,t3,t4;
 
+#
+# Bug #29104: assertion abort for a query with a view column reference
+#             in the GROUP BY list and a condition requiring the value  
+#             of another view column to be equal to a constant
+#
+
+CREATE TABLE t1 (a int, b int);
+INSERT INTO t1 VALUES (1,2), (2,2), (1,3), (1,2);
+
+CREATE VIEW v1 AS SELECT a, b+1 as b FROM t1;
+
+
+SELECT b, SUM(a) FROM v1 WHERE b=3 GROUP BY b;
+EXPLAIN SELECT b, SUM(a) FROM v1 WHERE b=3 GROUP BY b;
+
+SELECT a, SUM(b) FROM v1 WHERE b=3 GROUP BY a;
+EXPLAIN SELECT a, SUM(b) FROM v1 WHERE b=3 GROUP BY a;
+
+SELECT a, SUM(b) FROM v1 WHERE a=1 GROUP BY a;
+EXPLAIN SELECT a, SUM(b) FROM v1 WHERE a=1 GROUP BY a;
+
+DROP VIEW v1;
+DROP TABLE t1;
+
 --echo End of 5.0 tests.

sql/item.cc

@@ -1938,10 +1938,11 @@ bool Item_field::val_bool_result()
 
 bool Item_field::eq(const Item *item, bool binary_cmp) const
 {
-  if (item->type() != FIELD_ITEM)
+  Item *real_item= ((Item *) item)->real_item();
+  if (real_item->type() != FIELD_ITEM)
     return 0;
   
-  Item_field *item_field= (Item_field*) item;
+  Item_field *item_field= (Item_field*) real_item;
   if (item_field->field && field)
     return item_field->field == field;
   /*
@@ -5627,8 +5628,7 @@ bool Item_outer_ref::fix_fields(THD *thd, Item **reference)
   DESCRIPTION
     A view column reference is considered equal to another column
     reference if the second one is a view column and if both column
-    references resolve to the same item. It is assumed that both
-    items are of the same type.
+    references resolve to the same item.
 
   RETURN
     TRUE    Referenced item is equal to given item
@@ -5644,8 +5644,6 @@ bool Item_direct_view_ref::eq(const Item *item, bool binary_cmp) const
     if (item_ref->ref_type() == VIEW_REF)
     {
       Item *item_ref_ref= *(item_ref->ref);
-      DBUG_ASSERT((*ref)->real_item()->type() == 
-                  item_ref_ref->real_item()->type());
       return ((*ref)->real_item() == item_ref_ref->real_item());
     }
   }