Re: Comfortably check BackendPID with psql

On 12/06/2015 06:56, Noah Misch wrote:
> 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.
>

+1

> 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.
>
>

Tiny for me too, but I sometimes had the need.

I can't really see any good reason not to add a %p escape to psql's
PROMPT, so I'm attaching a simple patch to implement it. Unless someone
objects, I'll add it to the next commitfest.

--
Julien Rouhaud
http://dalibo.com - http://dalibo.org