Re: [HACKERS] PGXLOG variable worthwhile?

Marc G. Fournier wrote:
> On Tue, 17 Sep 2002, Bruce Momjian wrote:
>
> > Dave Page wrote:
> > > Which in this case is what puzzles me. We are only talking about a
> > > simple GUC variable after all - I don't know for sure, but I'm guessing
> > > it's not a huge effort to add one?
> >
> > Can we get agreement on that? A GUC for pg_xlog location? Much cleaner
> > than -X, doesn't have the problems of possible accidental use, and does
> > allow pg_xlog moving without symlinks, which some people don't like?
> >
> > If I can get a few 'yes' votes I will add it to TODO and do it for 7.4.
>
> Personally, I like the ability to define such at a command line level ...
> *especially* as it pertains to pointing to various directories ... I am
> against pulling the -X functionality out ... if you don't like it, don't
> use it ... add the GUC variable option to the mix, but don't take away
> functionality ...
>
> Hell, take a look at what you are saying above: because someone might
> forget to set -X, let's get rid of it in favor of a setting in a file that
> someone might forget to edit?
>
> Either format has the possibility of an error ... if you are so
> incompetent as to make that sort of mistake on a production server, it
> won't matter if its a GUC variable, environment variable or commnd line
> argument, you will still make that mistake ...

Sorry, I don't see the logic here. Using postgresql.conf, you set it
once and it remains set until you change it again. With -X, you have to
use it every time. I think that's where the votes came from.

You argued that -X and GUC make sense, but why add -X when can get it
done at once in postgresql.conf. Also, consider changing the location
does require moving the WAL files, so you already have this extra step.
Adding to postgresql.conf is easy. I don't think you can just point it
at a random empty directory on startup. Our goal was to reduce params
to postmaster/postgres in favor of GUC, not add to them.

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