Fixed #27632 -- Unified query parameters by their values on Oracle.

django/db/backends/oracle/base.py

@@ -450,7 +450,7 @@ class FormatStylePlaceholderCursor(object):
         else:
             return [p.force_bytes for p in params]
 
-    def _fix_for_params(self, query, params):
+    def _fix_for_params(self, query, params, unify_by_values=False):
         # cx_Oracle wants no trailing ';' for SQL statements.  For PL/SQL, it
         # it does want a trailing ';' but not a trailing '/'.  However, these
         # characters must be included in the original query in case the query
@@ -464,6 +464,18 @@ class FormatStylePlaceholderCursor(object):
             # Handle params as dict
             args = {k: ":%s" % k for k in params.keys()}
             query = convert_unicode(query % args, self.charset)
+        elif unify_by_values:
+            # Handle params as a dict with unified query parameters by their
+            # values. It can be used only in single query execute() because
+            # executemany() shares the formatted query with each of the params
+            # list. e.g. for input params = [0.75, 2, 0.75, 'sth', 0.75]
+            # params_dict = {0.75: ':arg0', 2: ':arg1', 'sth': ':arg2'}
+            # args = [':arg0', ':arg1', ':arg0', ':arg2', ':arg0']
+            # params = {':arg0': 0.75, ':arg1': 2, ':arg2': 'sth'}
+            params_dict = {param: ':arg%d' % i for i, param in enumerate(set(params))}
+            args = [params_dict[param] for param in params]
+            params = dict(zip(params_dict.values(), params_dict.keys()))
+            query = convert_unicode(query % tuple(args), self.charset)
         else:
             # Handle params as sequence
             args = [(':arg%d' % i) for i in range(len(params))]
@@ -471,7 +483,7 @@ class FormatStylePlaceholderCursor(object):
         return query, self._format_params(params)
 
     def execute(self, query, params=None):
-        query, params = self._fix_for_params(query, params)
+        query, params = self._fix_for_params(query, params, unify_by_values=True)
         self._guess_input_sizes([params])
         try:
             return self.cursor.execute(query, self._param_generator(params))

tests/aggregation_regress/tests.py

@@ -107,6 +107,19 @@ class AggregationTests(TestCase):
         for attr, value in six.iteritems(kwargs):
             self.assertEqual(getattr(obj, attr), value)
 
+    def test_annotation_with_value(self):
+        values = Book.objects.filter(
+            name='Practical Django Projects',
+        ).annotate(
+            discount_price=F('price') * 2,
+        ).values(
+            'discount_price',
+        ).annotate(sum_discount=Sum('discount_price'))
+        self.assertSequenceEqual(
+            values,
+            [{'discount_price': Decimal('59.38'), 'sum_discount': Decimal('59.38')}]
+        )
+
     def test_aggregates_in_where_clause(self):
         """
         Regression test for #12822: DatabaseError: aggregates not allowed in