# File lib/rubyrep/proxy_block_cursor.rb, line 71
    def update_checksum(row)
      dump = Marshal.dump(row)
      
      # updates row checksum array
      row_keys = row.reject {|key, | not primary_key_names.include? key}
      checksum = Digest::SHA1.hexdigest(dump)
      self.row_checksums << {:row_keys => row_keys, :checksum => checksum}

      # update the row cache (unless maximum cache size limit has already been reached)
      if current_row_cache_size + dump.size < max_row_cache_size
        self.current_row_cache_size += dump.size
        row_cache[checksum] = dump
      end
      
      # update current total checksum
      self.digest << dump
    end