Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.1138
diff -u -r1.1138 common.inc
--- includes/common.inc	28 Mar 2010 10:46:36 -0000	1.1138
+++ includes/common.inc	29 Mar 2010 04:42:56 -0000
@@ -5746,12 +5746,9 @@
     }
 
     if (!property_exists($object, $field)) {
-      // Skip fields that are not provided, unless we are inserting and a
-      // default value is provided by the schema.
-      if (!empty($primary_keys) || !isset($info['default'])) {
-        continue;
-      }
-      $object->$field = $info['default'];
+      // Skip fields that are not provided, default values are already known 
+      // by the database.
+      continue;
     }
 
     // Build array of fields to update or insert.
@@ -5841,6 +5838,15 @@
     $return = FALSE;
   }
 
+  // If we are inserting, populate empty fields with default values.
+  if (empty($primary_keys)) {
+    foreach ($schema['fields'] as $field => $info) {
+      if (!property_exists($object, $field) && isset($info['default'])) {
+        $object->$field = $info['default'];
+      }
+    }
+  }
+
   // If we began with an array, convert back so we don't surprise the caller.
   if ($array) {
     $object = (array) $object;