Re: [PATCH] Stop ALTER SYSTEM from making bad assumptions

Ian Barwick <ian(dot)barwick(at)2ndquadrant(dot)com> writes:
> On 8/6/19 11:16 AM, Stephen Frost wrote:
>>> Erm, those are duplicates though and we're saying that ALTER SYSTEM
>>> removes those... Seems like we should be normalizing the file to be
>>> consistent in this regard too.

> True. (Switches brain on)... Ah yes, with the patch previously provided
> by Tom, it seems to be just a case of replacing "strcmp" with "guc_name_compare"
> to match the existing string; the name will be rewritten with the value provided
> to ALTER SYSTEM, which will be normalized to lower case anyway.

Good catch.

>>> I dislike the special-casing of ALTER SYSTEM here, where we're basically
>>> saying that only ALTER SYSTEM is allowed to do this cleanup and that if
>>> such cleanup is wanted then ALTER SYSTEM must be run.

> This is just saying what ALTER SYSTEM will do, which IMHO we should describe
> somewhere. Initially when I stated working with pg.auto.conf I had
> my application append a comment line to show where the entries came from,
> but not having any idea how pg.auto.conf was modified at that point, I was
> wondering why the comment subsequently disappeared. Perusing the source code has
> explained that for me, but would be mighty useful to document that.

I feel fairly resistant to making the config.sgml explanation much longer
than what I wrote. That chapter is material that every Postgres DBA has
to absorb, so we should *not* be burdening it with stuff that few people
need to know.

Perhaps we could put some of these details into the Notes section of the
ALTER SYSTEM ref page. But I wonder how much of this is needed at all.

regards, tom lane