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

On Tue, Sep 10, 2013 at 3:53 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> writes:
>> On 2013-09-10 12:31:22 +0200, Magnus Hagander wrote:
>>> On Tue, Sep 10, 2013 at 5:29 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>>> 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).
>
>>> It's probably worth polling for that. I believe the jdbc driver at
>>> least has code for it, but I don't know if it's a requirement at this
>>> point.
>
>> Yes, it has code for it and I think it's still used pretty frequently to
>> circumvent prepared statement planning problems (misestimation,
>> indeterminate types). So I think we need convincing reasons to break
>> their usage.
>
> Note that I was proposing removing libpq's support for V2 connections.
> Not the backend's.

Oh. I blame the fact that we call the backend site libpq as well :)

Anyway. In that case, it seems a lot more reasonable. But definitely
not something backpatchable. But it's been a very long time since we
had a supported backend version that didn't speak v3.

The possible thing to consider there is if there's a common pg fork
that uses v2 only, that would then no longer be compatible with the
standard libpq. I have no idea if such a thing exists, and I'm not
sure we even care if it does, given how far behind they're lagging in
that case...

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/