Re: 'pg_ctl restart' confused about pathname to postgresql.conf

On Sat, Oct 22, 2011 at 12:13 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I think the reason it has a problem is that this is what's left in
> postmaster.opts:
>
> /home/tgl/pgsql/bin/postgres "-D" "baz"
>
> (which is an accurate representation of the command line from startup)
> and that -D switch gets fed to the postmaster as-is during restart.

I see.

> By and large, I would not recommend using a relative pathname to start
> the postmaster, unless you plan to start it from the same working
> directory every time.

Well, now I know. But that really seems like an annoying and arbitrary
restriction, not to mention not being documented anywhere AFAICT.

(I came upon this problem because I often set up servers with
binaries, libraries, and $PGDATA all tucked away under
/home/postgres/, and it seemed natural to use a relative pathname as
my data directory argument to pg_ctl since my working directory will
usually be /home/postgres/ when I'm poking at the server.)

> We could possibly avoid this by having pg_ctl try to absolute-ify the -D
> setting during postmaster start, but I'm not convinced it's worth the
> trouble, or even that it's appropriate for pg_ctl to editorialize on the
> user's choice of absolute vs relative path.

I don't want to bikeshed on the mechanics of how exactly this should
work, but it doesn't seem like it should be so hard to get this to
DWIM. In the example I posted, the last step which fails is basically:

  pg_ctl -D /tmp/foo/bar/baz/ restart

and it just seems totally broken for that to not work: pg_ctl knows
exactly which data directory the user means when invoked here. Plus,
these steps would work fine instead at that point:

  pg_ctl -D /tmp/foo/bar/baz/ stop
  pg_ctl -D /tmp/foo/bar/baz/ start

and I was under the impression (supported by the pg_ctl doc page,
which claims "restart mode effectively executes a stop followed by a
start") that these sequences should be equivalent.

Josh