def METHOD_NAME(self):
    """
    Perform any periodic database cleanup tasks.
    @returns: Deferred
    """
    # pass on this if we're not configured yet
    if not self.configured_url:
        return None
    d = self.changes.pruneChanges(self.master.config.changeHorizon)
    d.addErrback(log.err, 'while pruning changes')
    return d