Re: [HACKERS] [COMMITTERS] pgsql: Add psql variables showing serverversion and psql version.

On Tue, Sep 5, 2017 at 12:16 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Hm.  I think it would be a fine idea to push this change into v10,
> so that all psql versions that have \if would have these variables.
> However, I'm less enthused about adding them to the 9.x branches.
> Given the lack of \if, I'm not seeing a use-case that would justify
> taking any compatibility risk for.
>
> Opinions anyone?

As I see it, the risks of back-patching are:

1. Different minor versions will have different behavior, and that
tends to create more problems than it solves.

2. There's a small probability that somebody's script could be relying
on these variables to be initially unset.

I think back-patching these changes into stable branches is a slippery
slope that we'd be best advised not to go down.  I don't feel as
strongly about v10.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company