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diff --git a/src/mailman/model/uid.py b/src/mailman/model/uid.py
new file mode 100644
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+++ b/src/mailman/model/uid.py
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+# Copyright (C) 2011 by the Free Software Foundation, Inc.
+#
+# This file is part of GNU Mailman.
+#
+# GNU Mailman is free software: you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option)
+# any later version.
+#
+# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Unique IDs."""
+
+from __future__ import absolute_import, unicode_literals
+
+__metaclass__ = type
+__all__ = [
+    'UID',
+    ]
+
+
+from storm.locals import Int, Unicode
+
+from mailman.config import config
+from mailman.database.model import Model
+
+
+
+class UID(Model):
+    """Enforce uniqueness of uids through a database table.
+
+    This is used so that unique ids don't have to be tracked by each
+    individual model object that uses them.  So for example, when a user is
+    deleted, we don't have to keep separate track of its uid to prevent it
+    from ever being used again.  This class, hooked up to the
+    `UniqueIDFactory` serves that purpose.
+
+    There is no interface for this class, because it's purely an internal
+    implementation detail.
+
+    Since it's a hash, it's overwhelmingly more common for a uid to be
+    unique.
+    """
+    id = Int(primary=True)
+    uid = Unicode()
+
+    def __init__(self, uid):
+        super(UID, self).__init__()
+        self.uid = uid
+        config.db.store.add(self)
+
+    def __repr__(self):
+        return '<UID {0} at {1}>'.format(self.uid, id(self))
+
+    @staticmethod
+    def record(uid):
+        """Record the uid in the database.
+
+        :param uid: The unique id.
+        :type uid: unicode
+        :raises ValueError: if the id is not unique.
+        """
+        existing = config.db.store.find(UID, uid=uid)
+        if existing.count() != 0:
+            raise ValueError(uid)
+        return UID(uid)