public static UnsafeRow create8BytesFieldsRow(int numFields) {
        byte[] data = new byte[numFields * 8];
        UnsafeRow row = new UnsafeRow(numFields);
        row.pointTo(data, data.length);
        return row;
    }
Write the bytes of var-length field into ByteBuffer

Note: only work with HeapByteBuffer
indexr-query-opt/src/main/java/io/indexr/query/row/UnsafeRow.java