Re: Checkpoint cost, looks like it is WAL/CRC

Bruno Wolff III <bruno@wolff.to> writes:
> Are you sure about that? That would probably be the normal case, but are
> you promised that the hardware will write all of the sectors of a block
> in order?

I don't think you can possibly assume that.  If the block crosses a
cylinder boundary then it's certainly an unsafe assumption, and even
within a cylinder (no seek required) I'm pretty sure that disk drives
have understood "write the next sector that passes under the heads"
for decades.
        regards, tom lane