File systems usually allocate space in 4K chunks. If every row is a file, every row will have an average wasted space of 2K. Also, read/write efficiency decre

File systems usually allocate space in 4K chunks. If every row is a file, every row will have an average wasted space of 2K. Also, read/write efficiency decreases by an average of 50% because of this wasted space. It's similar to why backup programs (I'm the author of HashBackup) seem to go so slow on small files: if the average file size is 96 bytes, 4000 bytes (more than 97%) of I/O time is wasted reading such small files.