Date: Wed, 7 Feb 2024 10:54:21 +0100
From: Erik Wienhold <ewie@ewie.name>
To: Maiquel Grassi <grassi@hotmail.com.br>
Cc: Nathan Bossart <nathandbossart@gmail.com>, 
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: Psql meta-command conninfo+
Message-ID: <2quadime4klthrjwamiqmwqizfptoabi74dfjzzs3cjba4j6tp@lqzijrwi6i2o>
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On 2024-02-07 05:13 +0100, Maiquel Grassi wrote:
>   On Tue, Feb 06, 2024 at 09:45:54PM +0000, Maiquel Grassi wrote:
>   > My initial idea has always been that they should continue to appear
>   > because \conninfo+ should show all the things that \conninfo shows and
>   > add more information. I think that's the purpose of the 'plus.' Now we're
>   > on a better path than the initial one. We can still add the socket
>   > directory and the host.
> 
>   Agreed.
> 
> --//--
> 
> I believe it's resolved reasonably well this way:
> 
> SELECT
>   pg_catalog.current_database() AS "Database",
>   current_user AS "User",
>   pg_catalog.current_setting('server_version') AS "Server Version",
>   CASE
>     WHEN pg_catalog.inet_server_addr() IS NULL
>     THEN 'NULL'
>     ELSE pg_catalog.inet_server_addr()::text
>   END AS "Server Address",

Should be NULL instead of string 'NULL'.  So the entire CASE expression
is redundant and you can just return pg_catalog.inet_server_addr().

>   pg_catalog.current_setting('port') AS "Port",
>   CASE
>     WHEN pg_catalog.inet_client_addr() IS NULL
>     THEN 'NULL'
>     ELSE pg_catalog.inet_client_addr()::text
>   END AS "Client Address",
>   CASE
>     WHEN pg_catalog.inet_client_port() IS NULL
>     THEN 'NULL'
>     ELSE pg_catalog.inet_client_port()::text
>   END AS "Client Port",

Same here.

>   pg_catalog.pg_backend_pid() AS "Session PID",
>   CASE
>     WHEN pg_catalog.current_setting('unix_socket_directories') = ''
>     THEN 'NULL'
>     ELSE pg_catalog.current_setting('unix_socket_directories')
>   END AS "Socket Directory",

The CASE expression can be simplified to:

	nullif(pg_catalog.current_setting('unix_socket_directories'), '')

>   CASE
>     WHEN
>       pg_catalog.inet_server_addr() IS NULL
>       AND pg_catalog.inet_client_addr() IS NULL
>     THEN 'NULL'
>     WHEN
>       pg_catalog.inet_server_addr() = pg_catalog.inet_client_addr()
>     THEN 'localhost'

Is it safe to assume localhost here?  \conninfo prints localhost only
when I connect with psql -hlocalhost:

	$ psql -hlocalhost postgres
	psql (16.1)
	postgres=# \conninfo
	You are connected to database "postgres" as user "ewie" on host "localhost" (address "::1") at port "5432".
	postgres=# \q

	$ psql -h127.0.0.1 postgres
	psql (16.1)
	postgres=# \conninfo
	You are connected to database "postgres" as user "ewie" on host "127.0.0.1" at port "5432".

>     ELSE pg_catalog.inet_server_addr()::text
>   END AS "Host";

-- 
Erik