@Override
  public void cleanRecord(int recordId) throws IOException {
    checkRecordIdIsValid(recordId);

    //fill record with zeroes, by 4 bytes at once:
    assert RecordLayout.RECORD_SIZE_IN_BYTES % Integer.BYTES == 0
      : "RECORD_SIZE_IN_BYTES(=" + RecordLayout.RECORD_SIZE_IN_BYTES + ") is expected to be 32-aligned";

    int recordSizeInInts = RecordLayout.RECORD_SIZE_IN_BYTES / Integer.BYTES;

    long recordOffsetInFile = recordOffsetInFile(recordId);
    int recordOffsetOnPage = storage.toOffsetInPage(recordOffsetInFile);
    Page page = storage.pageByOffset(recordOffsetInFile);
    ByteBuffer pageBuffer = page.rawPageBuffer();
    for (int wordNo = 0; wordNo < recordSizeInInts; wordNo++) {
      int offsetOfWord = recordOffsetOnPage + wordNo * Integer.BYTES;
      setIntVolatile(pageBuffer, offsetOfWord, 0);
    }
  }
@Override
  public void cleanRecord(int recordId)