Re: [HACKERS] PGXLOG variable worthwhile?

Marc G. Fournier wrote:
> On Wed, 18 Sep 2002, Bruce Momjian wrote:
>
> > 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.
>
> Ah, so you are saying that you type out your full command line each and
> every time you start up the server? I know, in my case, I have a shell
> script setup that I edit my changes in so that I don't have to remember
> ...

Yep, but your central place for changes should be postgresql.conf, not
the command line. If we tried go get every GUC param on the command
line it would be unusable.

> > 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.
>
> I don't disagree that editing postgresql.conf is easy, but its not
> something that ppl would naturally thing of ... if I want to move a
> directory with most servers I run, I will generally do a man to find out
> what command options are required to do this change, and, if none are
> provided, just create a god-forsaken symlink ...
>
> The man page for postmaster should have something in it like:
>
> -X <directory> Specifies an alternate location for WAL files. Superseded
> by setting xlog_path in postmaster.conf
>
> Hell, if you are going to remove -X because its 'easier to do it in
> postmaster.conf', you should be looking at removing *all* command line
> args that are better represented in the postmaster.conf file ...

Well, those other options are things you may want to change frequently.
The xlog directory isn't going to be moving around, we hope. We have
the flags there only so they can be easily adjusted for testing, I
think, and in fact there has been discussion about removing more of
them.

> its nice to be able to do a simple ps to find out which process is which,
> and pointing where ... other then -D, I don't believe there is one option
> in there that I couldn't have set in the postmaster.conf file, but, then,
> to find out the various settings, I'd have to do ps to figure out where
> the database files are stored, and then go look at the postmaster.conf
> file to figure out what each are set to ...

Yea, but you aren't going to be needing to know the xlog directory that
way, will you?

Fact is, xlog is seldom moved, and symlinks do it fine now. The GUC was
a compromise for people who didn't like symlinks. If we are getting
pushback from GUC we may as well just drop the GUC idea and stick with
symlinks. I think that's how the vote went last time and it seems to be
heading in that direction again.

--
Bruce Momjian | http://candle.pha.pa.us
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