Re: Arbitary file size limit in twophase.c

Tom Lane wrote:
> "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> writes:
>> If we're going to check for file length, we should definitely check the
>> file length when we write it, so that we fail at PREPARE time, and not
>> at COMMIT time.
>
> I think this is mere self-delusion, unfortunately. You can never be
> certain at prepare time that a large alloc will succeed sometime later
> in a different process.
>
> Gavin's complaint is essentially that a randomly chosen hard limit is
> bad, and I agree with that. Choosing a larger hard limit doesn't make
> it less random.
>
> It might be worth checking at prepare that the file size doesn't exceed
> MaxAllocSize, but any smaller limit strikes me as (a) unnecessarily
> restrictive and (b) not actually creating any useful guarantee.

Hmm, I guess you're right.

Patch attached. I can't commit it myself right now, but will do so as
soon as I can, unless there's objections.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com