Re: Comfortably check BackendPID with psql

On Thu, Jun 11, 2015 at 04:05:13PM -0500, Jim Nasby wrote:
> On 6/11/15 4:55 AM, Andres Freund wrote:
> >On 2015-06-11 09:41:17 +0000, Naoya Anzai wrote:
> >>This is a so tiny patch but I think it is very useful for hackers and DBAs.
> >>When we debug with psql, we frequently use "SELECT pg_backend_pid();".
> >>This can change the input of the 24 characters to the only 4 characters!
> >
> >Not a big fan of that abbreviation itself. What I'd wondered about
> >instead - and actually had patched into my psql at some point - is
> >adding an appropriate escape to psql's PROMPT. I think that'd serve your
> >purpose as well?
> 
> +3.14159; that would be hugely helpful when using gdb.

You can get that today.  In ~/.psqlrc:

SELECT pg_catalog.pg_backend_pid() AS backend_pid \gset
\set PROMPT1 '%m %:backend_pid: %/%R%# '

It doesn't update after \connect, but the overlap between my use of \connect
and my use of debuggers is tiny.