Hi All,
I understand the storage layer in databases goes to great lengths to ensure:
- a row does not cross a block boundary
- read/writes/allocation happen in units of blocks
etc. The motivation is that at the OS level, it reads and writes pages (blocks), not individual bytes. I am only concerned about SSDs but I think the principle applies to HDD as well.
but how can we do all this when we are not even guaranteed that the beginning of a file will be aligned with a block boundary? refer this.
Further, I don't see any APIs exposing I/O operations in terms of blocks. All File I/O APIs I see expose a file as a randomly accessible contiguous byte buffer. Would it not have been easier if there were APIs that exposed I/O operations in terms of blocks?
can someone explain this to me?
Sid
