presto-spi/src/main/java/io/prestosql/spi/block/RowBlockBuilder.java/RowBlockBuilder/getSizeInBytes
class RowBlockBuilder:    @Override
    public long getSizeInBytes()
    {
        long sizeInBytes = (Integer.BYTES + Byte.BYTES) * (long) positionCount;
        for (int i = 0; i < numFields; i++) {
            sizeInBytes += fieldBlockBuilders[i].getSizeInBytes();
        }
        return sizeInBytes;
    }