public long readLongField(int fileId,
                            int fieldOffsetInRow) throws IOException {
    long offsetInFile = toOffsetInFile(fileId) + fieldOffsetInRow;
    int offsetInPage = storage.toOffsetInPage(offsetInFile);

    Page page = storage.pageByOffset(offsetInFile);
    ByteBuffer rawPageBuffer = page.rawPageBuffer();

    return (long)LONG_HANDLE.getVolatile(rawPageBuffer, offsetInPage);
  }
public long readLongField(int fileId,
                            int fieldOffsetInRow)