--- acl.install.old	2008-03-12 22:47:59.000000000 +0100
+++ acl.install	2008-05-13 16:56:03.000000000 +0200
@@ -169,3 +169,21 @@ function acl_update_5() {
   db_query("DELETE FROM {acl_user} WHERE uid NOT IN (SELECT uid FROM {users})");
   return $ret;
 }
+
+/**
+ * Insert priority column in {acl_node}.
+ */
+function acl_update_6() {
+  $ret = array();
+  switch ($GLOBALS['db_type']) {
+    case 'mysqli':
+    case 'mysql':
+      $ret[] = update_sql("ALTER TABLE {acl_node} ADD COLUMN priority tinyint(2) unsigned NOT NULL default '0' AFTER grant_delete");
+      break;
+
+    case 'pgsql':
+      $ret[] = update_sql('ALTER TABLE {acl_node} ADD COLUMN priority smallint NOT NULL default 0');
+      break;
+  }
+  return $ret;
+}