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

On Wed, Jul 19, 2017 at 8:56 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> 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");

+1. Even if it just gets triggered in 20 years by some hacker, that's
a good reminder about assumptions behind the update logic.
-- 
Michael