Обсуждение: Getting process id of a connection?

Hi all,

Is there a way to determine the pid of a database connection from
within that connection?

As a hypothetical example, I would like to be able to do the following:

$ps x
  PID TTY      STAT   TIME COMMAND
11674 ?        S      0:00 sshd: webbs@pts/1
11675 pts/1    Ss     0:00 -bash
11682 pts/1    T      0:00 psql
11685 pts/1    R+     0:00 ps x

psql=# select CURRENT_PID;
11682

I want this so that I can log the psycopg2 connection pid, and kill it
to test reconnection code.

Thanks!
-W

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On Fri, 4 Jan 2008 14:59:47 -0800
"Webb Sprague" <webb.sprague@gmail.com> wrote:

> Hi all,
> 
> Is there a way to determine the pid of a database connection from
> within that connection?
> 
> As a hypothetical example, I would like to be able to do the
> following:
> 
> $ps x
>   PID TTY      STAT   TIME COMMAND
> 11674 ?        S      0:00 sshd: webbs@pts/1
> 11675 pts/1    Ss     0:00 -bash
> 11682 pts/1    T      0:00 psql
> 11685 pts/1    R+     0:00 ps x
> 
> psql=# select CURRENT_PID;
> 11682
> 
> I want this so that I can log the psycopg2 connection pid, and kill it
> to test reconnection code.

postgres=# select procpid from pg_stat_activity;
 procpid 
- ---------
   30851
   17510
    4496
   20237
    1305
(5 rows)


Sincerely,

Joshua D. Drake

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Webb Sprague wrote:
> Hi all,
>
> Is there a way to determine the pid of a database connection from
> within that connection?
>
> As a hypothetical example, I would like to be able to do the following:
>
> $ps x
>   PID TTY      STAT   TIME COMMAND
> 11674 ?        S      0:00 sshd: webbs@pts/1
> 11675 pts/1    Ss     0:00 -bash
> 11682 pts/1    T      0:00 psql
> 11685 pts/1    R+     0:00 ps x
>
> psql=# select CURRENT_PID;
> 11682
>
> I want this so that I can log the psycopg2 connection pid, and kill it
> to test reconnection code.
>
> Thanks!
> -W

I think select pg_backend_pid(); will do that.

Joshua D. Drake wrote:
> On Fri, 4 Jan 2008 14:59:47 -0800
> "Webb Sprague" <webb.sprague@gmail.com> wrote:
>
>> Hi all,
>>
>> Is there a way to determine the pid of a database connection from
>> within that connection?
>>
>> As a hypothetical example, I would like to be able to do the
>> following:
>>
>> $ps x
>>   PID TTY      STAT   TIME COMMAND
>> 11674 ?        S      0:00 sshd: webbs@pts/1
>> 11675 pts/1    Ss     0:00 -bash
>> 11682 pts/1    T      0:00 psql
>> 11685 pts/1    R+     0:00 ps x
>>
>> psql=# select CURRENT_PID;
>> 11682
>>
>> I want this so that I can log the psycopg2 connection pid, and kill it
>> to test reconnection code.
>
> postgres=# select procpid from pg_stat_activity;
>  procpid
> - ---------
>    30851
>    17510
>     4496
>    20237
>     1305
> (5 rows)

I think he's looking for the pid of the client, not the server.

cww=# select procpid from pg_stat_activity;
  procpid
---------
     8902
(1 row)

  8902 ?        Ss     0:00  \_ postgres: cww cww 192.168.171.100(40424)
idle

Colin

>
> I think select pg_backend_pid(); will do that.

Perfect.  I tried googling but I didn't try \df *pid* which would have found it

I tried to figure out the pg_stat_activity, but I can't think of a
WHERE condition that would make it give me the info I wanted.

Thx again to everyone.