Re: Protocol forced to V2 in low-memory conditions?

Maciek Sakrejda <m(dot)sakrejda(at)gmail(dot)com> writes:
> One of our customers seems to be running into exactly the issue
> hypothesized about by Tom here:
> http://www.postgresql.org/message-id/8040.1314403175@sss.pgh.pa.us
> Was the possibility of an inadvertent protocol downgrade addressed as part
> of that patch? I read through the thread, but it wasn't entirely clear.

No, a quick look at report_fork_failure_to_client shows it still always
sends V2 protocol. We fixed some of the lesser issues discussed in that
thread, but I don't think we ever agreed how to deal with this one.

I've been thinking of late that it might be time to retire libpq's
support for V2 protocol (other than in the specific context of the first
error message received while trying to make a connection). If we did
that, we'd remove the code path that thinks it should downgrade to V2
protocol, and thus fix this problem by removing code not adding more.

However, that doesn't sound like a back-patchable solution, and also
it remains unclear whether non-libpq clients such as JDBC have an issue
with this.

regards, tom lane