code: func EncodeRecordKey(recordPrefix kv.Key, h int64) kv.Key {
  	buf := make([]byte, 0, len(recordPrefix)+idLen)
  	buf = append(buf, recordPrefix...)
  	buf = codec.EncodeInt(buf, h)
  	return buf
  }
docs: // EncodeRecordKey encodes the recordPrefix, row handle into a kv.Key.