Lookup the integer ID associated with each (namespace, key) in the
        keys list

def lookup_ids(self, keys):
        """Lookup the integer ID associated with each (namespace, key) in the
        keys list"""
        keys_len = len(keys)
        ids = {namespace_key: None for namespace_key in keys}
        start = 0
        bulk_insert = self.bulk_insert
        query = 'SELECT namespace, key, id FROM gauged_keys WHERE '
        check = '(namespace = %s AND key = %s) '
        cursor = self.cursor
        execute = cursor.execute
        while start < keys_len:
            rows = keys[start:start+bulk_insert]
            params = [param for params in rows for param in params]
            id_query = query + (check + ' OR ') * (len(rows) - 1) + check
            execute(id_query, params)
            for namespace, key, id_ in cursor:
                ids[(namespace, key)] = id_
            start += bulk_insert
        return ids