Re: expose parallel leader in CSV and log_line_prefix

Justin Pryzby <pryzby@telsasoft.com>

From: Justin Pryzby <pryzby@telsasoft.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Julien Rouhaud <rjuju123@gmail.com>, Daniel Gustafsson <daniel@yesql.se>, pgsql-hackers@postgresql.org
Date: 2020-07-10T02:20:23Z
Lists: pgsql-hackers
On Fri, Jul 10, 2020 at 11:09:40AM +0900, Michael Paquier wrote:
> On Thu, Jul 09, 2020 at 01:53:39PM +0200, Julien Rouhaud wrote:
> > Sure!  I've been quite busy with internal work duties recently but
> > I'll review this patch shortly.  Thanks for the reminder!
> 
> Hmm.  In which cases would it be useful to have this information in
> the logs knowing that pg_stat_activity lets us know the link between
> both the leader and its workers?

PSA is an instantaneous view whereas the logs are a record.  That's important
for shortlived processes (like background workers) or in the case of an ERROR
or later crash.

Right now, the logs fail to include that information, which is deficient.  Half
the utility is in showing *that* the log is for a parallel worker, which is
otherwise not apparent.

-- 
Justin



Commits

  1. Add %P to log_line_prefix for parallel group leader

  2. Tweak behavior of pg_stat_activity.leader_pid

  3. Add leader_pid to pg_stat_activity