Even in ZFS, there is more overhead for a file than I would guess a database has for a row. Each file needs a DNode, which is 512 bytes. It also needs an entry

Even in ZFS, there is more overhead for a file than I would guess a database has for a row. Each file needs a DNode, which is 512 bytes. It also needs an entry in it's parent directory's list of files (a 64 byte micro ZAP entry for example).