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

Buch (buchen sollst du suchen), Buchhaltung is great. Thanks for the
writing.

Stephen Frost <sfrost(at)snowman(dot)net> schrieb am Mo., 5. Aug. 2019, 21:02:

> Greetings,
>
> On Mon, Aug 5, 2019 at 14:43 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
>> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> > On Mon, Aug 5, 2019 at 2:29 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> >> I think Stephen is not being unreasonable to suggest that we need some
>> >> documentation about what external tools may safely do to pg.auto.conf.
>> >> So somebody's got to write that.
>>
>> > I mean, really? We're going to document that if you want to add a
>> > setting to the file, you can just append it, but that if you find
>> > yourself desirous of appending so many settings that the entire disk
>> > will fill up, you should maybe reconsider? Perhaps I'm being mean
>> > here, but that seems like it's straight out of the
>> > blinding-flashes-of-the-obvious department.
>>
>> I don't think we need to go on about it at great length, but it seems
>> to me that it'd be reasonable to point out that (a) you'd be well
>> advised not to touch the file while the postmaster is up, and (b)
>> last setting wins. Those things are equally true of postgresql.conf
>> of course, but I don't recall whether they're already documented.
>
>
> Folks certainly modify postgresql.conf while the postmaster is running
> pretty routinely, and we expect them to which is why we have a reload
> option, so I don’t think we can say that the auto.conf and postgresql.conf
> are to be handled in the same way.
>
> Last setting wins, duplicates should be ignored and may be removed,
> comments should be ignored and may be removed, and appending to the file is
> acceptable for modifying a value. I’m not sure how much we really document
> the structure of the file itself offhand- back when users were editing it
> we could probably be a bit more fast and loose with it, but now that we
> have different parts of the system modifying it along with external tools
> doing so, we should probably write it down a bit more clearly/precisely.
>
> I suspect the authors of pg_conftool would appreciate that too, so they
> could make sure that they aren’t doing anything unexpected or incorrect.
>
> Thanks,
>
> Stephen
>
>>