Re: [HACKERS] initdb change

On Mon, Aug 25, 2008 at 09:54:26AM -0700, Joshua D. Drake wrote:
> On Mon, 25 Aug 2008 09:42:21 -0700
> David Fetter <david@fetter.org> wrote:
>
> > > We either need to provide a way to initialize it at initdb, allow
> > > xlogs to be in table space or add a GUC for the location.
> >
> > There's already a way to specify where xlogs should be via
> > -X/--xlogdir.
>
> Sorry should have checked 8.3 initdb instead of 8.2.
>
> > What that doesn't do is put the xlogdir where a DBA
> > would naturally expect to find it. When that DBA doesn't find it in
> > the place they expect, very bad knock-on decisions are likely to
> > result.
>
> O.k. when using 8.3 I did this:
>
> initdb -D /tmp/foo -X /tmp/xlogs
>
> And I got:
>
> /tmp/foo/pg_xlog which is a link to /tmp/xlogs

Oops. Well, this isn't quite the foot-gun I'd previously thought :P

> That seems perfectly logical. If I (without removing the old initdb) do
> this:
>
> /usr/lib/postgresql/8.3/bin/initdb -D /tmp/bar -X /tmp/xlog
>
> I get:
>
> initdb: directory "/tmp/xlog" exists but is not empty
> If you want to store the transaction log there, either
> remove or empty the directory "/tmp/xlog".
> initdb: removing data directory "/tmp/bar"
>
> I just reread your original message a little slower and see that what
> you want is if:
>
> /var/lib/pgsql/data/ exists but is empty you can initdb within that
> directory. However if there is anything in it you can not. You are
> asking that if pg_xlog exists but is empty that we still be able to use
> the DATADIR and you can pass existing so that it will also use pg_xlog
> if it is empty.
>
> My take would be to not add a new flag. Instead to implicitly allow it.
> If initdb finds that DATADIR and pg_xlog is empty it will use both.

Is there some reason why initdb shouldn't just Do The Right Thing™
when it finds an empty extant $PGDATA/pg_xlog directory that passes
the same tests an empty extant $PGDATA would?

Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david.fetter@gmail.com

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