Ticket #3541: cache_count.patch

django/db/models/query.py

@@ -194 +194 @@
                 yield obj
 
     def count(self):
-        "Performs a SELECT COUNT() and returns the number of records as an integer."
+        """
+        Returns the number of records as an integer.
+        
+        If _result_cache has been loaded, do len(self._result_cache)
+        otherwise perform a SELECT COUNT().
+        """
+        if hasattr(self, '_result_count'):
+            return self._result_count
+        if self._result_cache is not None:
+            self._result_count = len(self._result_cache)
+            return self._result_count
         counter = self._clone()
         counter._order_by = ()
         counter._select_related = False
@@ -225 +235 @@
         if limit:
             count = min(limit, count)
 
+        self._result_count = count
         return count
 
     def get(self, *args, **kwargs):