Re: Psql meta-command conninfo+

Hi, Maiquel!

The patch v10 build ends with a warning:
$ make -j --silent
describe.c:911:1: warning: no previous prototype for ‘listConnectionInformation’ [-Wmissing-prototypes]  911 | listConnectionInformation()      | ^~~~~~~~~~~~~~~~~~~~~~~~~

About terms.

postgres@postgres(17.0)=# \x \conninfo+
Expanded display is on.
Current Connection Information
-[ RECORD 1 ]------+---------
Database           | postgres
Authenticated User | postgres
System User        | 
Current User       | postgres
Session User       | postgres
Session PID        | 951112
Server Version     | 17devel
Server Address     | 
Server Port        | 5401
Client Address     | 
Client Port        | 
Socket Directory   | /tmp
Host               | 

It looks like "Session PID" is a new term for the server process identifier.
How about changing the name to "Backend PID" (from pg_backend_pid) or even PID (from pg_stat_activity)?

> 1.
> +			if (db == NULL)
> +				printf(_("You are currently not connected to a database.\n"));
> 
> This check is performed for \conninfo, but not for \conninfo+.

P {margin-top:0;margin-bottom:0;}

1. The connection check for the case of \conninfo+ is handled by "describe.c" itself since it deals with queries. I might be mistaken, but I believe that by using "printQuery()" via "describe.c", this is already ensured, and there is no need to evaluate the connection status.

I found that \conninfo and \conninfo+ act differently when the connection is broken.
I used pg_terminate_backend function from another session to terminate an open psql session.
After that, \conninfo does not see the connection break (surprisingly!), and \conninfo+ returns an error:

postgres@postgres(17.0)=# \conninfo+
FATAL:  terminating connection due to administrator command
server closed the connection unexpectedly	This probably means the server terminated abnormally	before or while processing the request.
The connection to the server was lost. Attempting reset: Succeeded.

postgres@postgres(17.0)=# \conninfo
You are connected to database "postgres" as user "postgres" via socket in "/tmp" at port "5401".

Another surprise is that this check: if (db == NULL) did not work in both cases.

-- 
Pavel Luzanov
Postgres Professional: https://postgrespro.com