Re: Is it time to kill support for very old servers?

On Fri, Oct 7, 2016 at 4:06 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> pg_dump alleges support for dumping from servers back to 7.0. Would v10
> be a good time to remove some of that code? It's getting harder and
> harder to even compile those ancient branches, let alone get people to
> test against them (cf. 4806f26f9). My initial thought is to cut support
> for pre-7.3 or maybe pre-7.4 servers, as that would allow removal of
> support for cases where the server lacks schemas or pg_depend, each of
> which requires a fair deal of klugery in pg_dump.
>

+1 for doing it, and also picking a version that's "easily explainable". If
we can say "now we support back to 8.0" that's a lot better than saying 8.1
or 7.4.

> In the same line, maybe we should kill libpq's support for V2 protocol
> (which would make the cutoff 7.4). And maybe the server's support too,
> though that wouldn't save very much code. The argument for cutting this
> isn't so much that we would remove lots of code as that we're removing
> code that never gets tested, at least not by us.
>

Which is a pretty strong argument in itself.

> One small problem with cutting libpq's V2 support is that the server's
> report_fork_failure_to_client() function still sends a V2-style message.
> We could change that in HEAD, certainly, but we don't really want modern
> libpq unable to parse such a message from an older server. Possibly we
> could handle that specific case with a little special-purpose code and
> still be able to take out most of fe-protocol2.c.
>
> Thoughts?
>

I agree we want the new libpq to be able to deal with that one from old
versions, because 9.6 isn't really old yet. We *should* probably change it
in head for the future anyway, but that means we have to keep it around in
libpq for quite a long while anyway.

Unless the special purpose code becomes long and complicated, I think
that's the best way to do it.

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