code: def insert_or_append_blocks(self, blocks):
          
          binary = self.psycopg2.Binary
          execute = self.cursor.execute
          query = 'UPDATE gauged_data SET data = data || %s, flags = %s ' \
              'WHERE namespace = %s AND "offset" = %s AND key = %s; ' \
              'INSERT INTO gauged_data (data, flags, namespace, "offset", key)' \
              'SELECT %s, %s, %s, %s, %s WHERE NOT EXISTS (' \
              'SELECT 1 FROM gauged_data WHERE namespace = %s ' \
              'AND "offset" = %s AND key = %s)'
          for namespace, offset, key, data, flags in blocks:
              data = binary(data)
              execute(query, (data, flags, namespace, offset, key, data, flags,
                              namespace, offset, key, namespace, offset, key))
docs: Insert multiple blocks. If a block already exists, the data is
          appended. blocks must be a list of tuples where each tuple consists
          of (namespace, offset, key, data)