Re: Re: protocol version negotiation (Re: Libpq PGRES_COPY_BOTH - version compatibility)

Okay, I will add a mechanism to try connecting with 3.0 if 3.1 fails- that should be a few lines of code fe-connect.c; this will eliminate the need for a back-patch. What do you think of the rest of the change?

Thanks,
Badrul

-----Original Message-----
From: Robert Haas [mailto:robertmhaas(at)gmail(dot)com]
Sent: Wednesday, October 4, 2017 4:54 AM
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Badrul Chowdhury <bachow(at)microsoft(dot)com>; Satyanarayana Narlapuram <Satyanarayana(dot)Narlapuram(at)microsoft(dot)com>; Craig Ringer <craig(at)2ndquadrant(dot)com>; Peter Eisentraut <peter_e(at)gmx(dot)net>; Magnus Hagander <magnus(at)hagander(dot)net>; PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] Re: protocol version negotiation (Re: Libpq PGRES_COPY_BOTH - version compatibility)

On Tue, Oct 3, 2017 at 9:46 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Badrul Chowdhury <bachow(at)microsoft(dot)com> writes:
>> 1. Pgwire protocol v3.0 with negotiation is called v3.1.
>> 2. There are 2 patches for the change: a BE-specific patch that will be backported and a FE-specific patch that is only for pg10 and above.
>
> TBH, anything that presupposes a backported change in the backend is
> broken by definition. We expect libpq to be able to connect to older
> servers, and that has to include servers that didn't get this memo.
>
> It would be all right for libpq to make a second connection attempt if
> its first one fails, as we did in the 2.0 -> 3.0 change.

Hmm, that's another approach, but I prefer the one advocated by Tom Lane.

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