Re: Something for the TODO list: deprecating abstime and friends

I wrote:
> Hm. Currently sizeof(struct ControlFileData) = 296, at least on my
> machine. Letting it grow past 512 would be problematic. It's hard
> to see getting to that any time soon, though; we don't add fields
> there often.

I wonder if it'd be worth the trouble to stick something like this into
xlog.c:

/*
* For reliability's sake, it's critical that pg_control updates
* be atomic writes. That generally means the active data can't
* be more than one disk sector, which is 512 bytes on common
* hardware. Be very careful about raising this limit.
*/
StaticAssertStmt(sizeof(ControlFileData) <= 512,
"pg_control is too large for atomic disk writes");

regards, tom lane