diff -Naur drupal-5.0-beta1.orig/modules/system/system.install drupal-5.0-beta1/modules/system/system.install
--- drupal-5.0-beta1.orig/modules/system/system.install	2006-10-31 16:55:17.000000000 +0200
+++ drupal-5.0-beta1/modules/system/system.install	2006-11-22 12:13:31.000000000 +0200
@@ -236,7 +236,8 @@
         filepath varchar(255) NOT NULL default '',
         filemime varchar(255) NOT NULL default '',
         filesize int unsigned NOT NULL default 0,
-        PRIMARY KEY (fid)
+        PRIMARY KEY (fid),
+        INDEX nid (nid)
       ) /*!40100 DEFAULT CHARACTER SET UTF8 */ ");
 
       db_query("CREATE TABLE {file_revisions} (