Azure's BlobbInputStream internally buffers 4 MB of data irrespective of the data length requested for. This would be beneficial for sequential reads. However, for positional reads (seek to specific location, read x number of bytes, seek back to original location) this may not be beneficial and might even download lot more data which are not used later.
It would be good to override readFully(long position, byte buffer, int offset, int length) for NativeAzureFsInputStream and make use of mark(readLimit) as a hint to Azure's BlobInputStream.
BlobInputStream can consider this as a hint later to determine the amount of data to be read ahead. Changes to BlobInputStream would not be addressed in this JIRA.