diff --git a/README.mkd b/README.mkd
index aabd0cc..2b84eb8 100644
--- a/README.mkd
+++ b/README.mkd
@@ -5,7 +5,7 @@ Edit a copy of `archrepo.ini` and then run `./archreposrv <config>`.
 DEPENDENCIES
 ====
 
-* Python, &gt;= 3.3
+* Python, &gt;= 3.3, with gdbm support
 * tornado, > 2.4.1
 * pyinotify, tested 0.9.4
 * winterpy
diff --git a/archrepo.ini b/archrepo.ini
index 7ac1d6e..fbf954f 100644
--- a/archrepo.ini
+++ b/archrepo.ini
@@ -8,6 +8,9 @@ name: archlinuxcn
 # files in this directory, remember to update the configuration of inotify.
 path: /home/lilydjwg/tmpfs/test
 
+# A database to store package filenames. Default to ${path}/repofiles.db
+#files-db: /home/lilydjwg/tmpfs/test/repofiles.db
+
 # Specify where to find these commands
 #command-add: repo-add
 #command-remove: repo-remove
diff --git a/archreposrv b/archreposrv
index 12ff2cd..111b97d 100755
--- a/archreposrv
+++ b/archreposrv
@@ -7,6 +7,7 @@ import configparser
 from functools import partial
 import queue
 import logging
+import dbm.gnu
 
 import pyinotify
 from tornado.ioloop import IOLoop
@@ -16,6 +17,8 @@ import archpkg
 from myutils import enable_pretty_logging
 enable_pretty_logging(logging.DEBUG)
 
+# FIXME: 如果一个软件包消失了，那么如果它在仓库数据库里，它就应当从数据库删除。否则不应该
+
 class ActionInfo:
   def __init__(self, path, action):
     self.pkginfo = archpkg.parsePkgName(path)
@@ -116,11 +119,13 @@ class RepoMan:
 class EventHandler(pyinotify.ProcessEvent):
   def my_init(self, config, wm, ioloop=None):
     self.moved_away = {}
-    self.files = files = set()
     self.repomans = {}
     self._ioloop = ioloop or IOLoop.instance()
 
     base = config.get('path')
+    dbname = config.get('files-db', os.path.join(base, 'repofiles.db'))
+    self._db = dbm.gnu.open(dbname, 'cs')
+
     dirs = [os.path.join(base, x) for x in ('any', 'i686', 'x86_64')]
 
     for d in dirs:
@@ -128,6 +133,15 @@ class EventHandler(pyinotify.ProcessEvent):
       wm.add_watch(d, pyinotify.ALL_EVENTS)
       self.repomans[d] = RepoMan(config, d, self._ioloop)
 
+    self._initial_update(files)
+
+  def _initial_update(self, files):
+    oldfiles = {f.decode('utf-8') for f in self._db.keys()}
+    for f in files - oldfiles:
+      self.dispatch(f, 'add')
+    for f in oldfiles - files:
+      self.dispatch(f, 'remove')
+
   def process_IN_CLOSE_WRITE(self, event):
     logging.debug('Writing done: %s', event.pathname)
     self.dispatch(event.pathname, 'add')
@@ -188,7 +202,7 @@ class EventHandler(pyinotify.ProcessEvent):
         newpath = os.path.join(newd, file)
         if action == 'add':
           os.symlink(os.path.join('..', arch, file), newpath)
-          self.repomans[newd].add_action(ActionInfo(newpath, action))
+          self._real_dispatch(newd, ActionInfo(newpath, action))
         else:
           try:
             os.unlink(newpath)
@@ -197,6 +211,18 @@ class EventHandler(pyinotify.ProcessEvent):
             # someone deleted the file for us
             pass
 
+    self._real_dispatch(d, act)
+
+  def _real_dispatch(self, d, act):
+    key = act.path.encode('utf-8')
+    if act.action == 'add':
+      self._db[key] = b'\x01'
+    else:
+      try:
+        del self._db[key]
+      except KeyError:
+        logging.warn('files db inconsistent: key %s not there', key)
+
     self.repomans[d].add_action(act)
 
   # def process_default(self, event):