RE: Psql meta-command conninfo+

On Sat, Feb 17, 2024 at 02:53:43PM +0000, Maiquel Grassi wrote:
>> The "pg_stat_ssl" view is available from >= PG 9.5, and the "pg_stat_gssapi" view is
>> available from >= PG 12. The "compression" column was removed from the
>> "pg_stat_ssl" from >= PG 14. All of these cases introduce greater complexity in
>> maintaining the SQL. The central idea from the beginning has always been to show
>> the user all the information from \conninfo and extend it in \conninfo+.

>IMHO we should use the views whenever possible (for the reason stated
>above [0]).  I think it's okay if we need to fall back to a different
>approach for older versions.  But presumably we'll discontinue psql support
>for these old server versions at some point, at which point we can simply
>delete the dead code that doesn't use the views.

>> The absence
>> of the "compression" column in version 14 and above makes dealing with this even
>> more complicated, and not showing it seems to contradict \conninfo.

>I would be okay with using PQsslAttribute() for all versions for this one
>since any remaining support for this feature is on its way out.  Once psql
>no longer supports any versions that allow SSL compression, we could
>probably remove it from \conninfo[+] completely or hard-code it to "off".

>> SSL support has been available since version 7.1 (see documentation); if there was
>> support before that, I can't say. In this regard, it may seem strange, but there are still
>> many legacy systems running older versions of PostgreSQL. Just yesterday, I assisted
>> a client who is still using PG 8.2. In these cases, using the "pg_stat_ssl" and
>> "pg_stat_gssapi" views would not be possible because they don't exist on the server.
>> I believe that psql should cover as many cases as possible when it comes to compatibility
>> with older versions (even those no longer supported). In this case, concerning SSL and
>> GSS, I think libpq is better prepared to handle this.

>At the moment, the psql support cutoff appears to be v9.2 (see commit
>cf0cab8), which has been out of support for over 6 years.  If \conninfo+
>happens to work for older versions, then great, but I don't think we should
>expend too much energy in this area.

[0] https://postgr.es/m/20240216155449.GA1236054%40nathanxps13

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Hi Nathan!

Sorry for the delay. I will make the adjustments as requested soon.

Regards,
Maiquel Grassi.