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

On Tue, Sep 10, 2013 at 03:55:30PM +0200, Magnus Hagander wrote:
> 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...

How could we care anyhow? It's not like we have the resources to
maintain all our current released versions anyhow, e.g. current
support for 8.4 is a good bit less solid than for 9.2.

Cheers,
David.
--
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