code: func EncodeIndexSeekKey(tableID int64, idxID int64, encodedValue []byte) kv.Key {
  	key := make([]byte, 0, prefixLen+len(encodedValue))
  	key = appendTableIndexPrefix(key, tableID)
  	key = codec.EncodeInt(key, idxID)
  	key = append(key, encodedValue...)
  	return key
  }
docs: // EncodeIndexSeekKey encodes an index value to kv.Key.