presto-rcfile/src/main/java/io/prestosql/rcfile/RcFileReader.java/RcFileReader/readOffsets
class RcFileReader:        private int[] readOffsets(int batchSize)
                throws IOException
        {
            int[] offsets = new int[batchSize + 1];
            offsets[0] = currentOffset;
            for (int i = 0; i < batchSize; i++) {
                int valueLength = readNextValueLength();
                offsets[i + 1] = offsets[i] + valueLength;
            }
            currentOffset = offsets[batchSize];
            currentPosition += batchSize;
            return offsets;
        }