Re: deadlock_timeout at < PGC_SIGHUP?

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Tue, Mar 29, 2011 at 1:38 AM, Noah Misch <noah(at)leadboat(dot)com> wrote:
>> What is notable/surprising about the behavior when two backends have different
>> values for deadlock_timeout?

> I'd be inclined to think that PGC_SUSET is plenty. It's actually not
> clear to me what the user could usefully do other than trying to
> preserve his transaction by setting a high deadlock_timeout - what is
> the use case, other than that?

Yeah, that was my reaction too: what is the use case for letting
different backends have different settings? It fails to give any real
guarantees about who wins a deadlock, and I can't see any other reason
for wanting session-specific settings.

I don't know how difficult a priority setting would be. IIRC, the
current deadlock detector always kills the process that detected the
deadlock, but I *think* that's just a random choice and not an essential
feature. If so, it'd be pretty easy to instead kill the lowest-priority
xact among those involved in the deadlock.

regards, tom lane