Re: GUC with units, details

Tom Lane wrote:
> Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
>> Tom Lane wrote:
>>> Peter's not said exactly how he plans to deal with
>>> this, but I suppose it'll round off one way or the other ...
>
>> It'll get truncated by integer division. I wouldn't mind if someone
>> proposed a patch to create a warning or error in this case, but I
>> wanted to keep the initial version simple.
>
> I'd recommend against that. Apple recently changed OS X so that
> it rejects SHMMAX settings that aren't an exact multiple of
> something-or-other, and I've found that to be a *serious* PITA.
> Of course part of the problem is that there's no helpful message,
> but it's still a big loss from a usability standpoint, and quite
> unnecessary (every other Unix seems willing to round off...)
>
> One thought is that maybe we should round up not down? I'm having
> a hard time making a specific case either way, though.

Rounding up would have the advantage that you could just specify "0"
in the config file, and have postgres use the smallest value possible.

greetings, Florian Pflug