Re: let's make the list of reportable GUCs configurable (was Re: Add%r substitution for psql prompts to show recovery status)
От | Craig Ringer |
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Тема | Re: let's make the list of reportable GUCs configurable (was Re: Add%r substitution for psql prompts to show recovery status) |
Дата | |
Msg-id | CAMsr+YEEFXz_QPiGu-FND+sXJ6Mmi80i4Q43CNVNH2UQf+8-Uw@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: let's make the list of reportable GUCs configurable (was Re: Add %r substitution for psql prompts to show recovery status) (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: let's make the list of reportable GUCs configurable (was Re: Add%r substitution for psql prompts to show recovery status)
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Список | pgsql-hackers |
On 11 January 2018 at 09:55, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Robert Haas <robertmhaas@gmail.com> writes:
> But if we add this feature and somebody wants to use it for
> server_version_num, it's really pretty simple. In the startup packet,
> you say _pq_.report=server_version_num. Then, you call
> PQparameterStatus(conn, "server_version_num"). If you don't get a
> value, you try calling PQparameterStatus(conn, "server_version") and
> extracting the second word. If that still doesn't work then you give
> up. That doesn't seem either useless or difficult to implement
> correctly from here.
Yeah, but what's the point? If yuou have to maintain the server_version
parsing code anyway, you're not saving any complexity with this. You're
just creating a code backwater that you probably won't test adequately.
If we'd done server_version_num in 9.5, for example, less stuff would've broken with pg10.
I just don't get it. The argument you use can be applied to almost any change, to say "why bother making change <x> because people can't rely on it for <y> years, so it's pointless to have it at all". Why add protocol v3?
PostgreSQL is a stable, long term project, and I'd like to plan for the future. I also think people are way more likely to handle things like --with-extra-version correctly when dealing with server_version_num, where I don't much *care* if code parsing old server versions breaks.
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