Re: CompactCheckpointerRequestQueue versus pad bytes

I wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> So I'm having a hard time understanding under what imaginable set of
>> circumstances this might break.

> Padding inside RelFileNodeBackend would break it, because
> ForwardFsyncRequest copies the rnode as a struct.  So that's why I'm
> asking whether we want to establish an explicit requirement that that
> struct not contain any padding.

BTW, I'd be a lot happier about assuming that bare RelFileNode contains
no padding, because that's at least got all the fields the same type.
So that brings us back to the question of why this code is supporting
fsync requests for local relations in the first place.  Couldn't we have
it ignore those, and then only ship RelFileNode to the checkpointer?

			regards, tom lane