Re: [PATCH] Stop ALTER SYSTEM from making bad assumptions - Mailing list pgsql-hackers

From Stephen Frost
Subject Re: [PATCH] Stop ALTER SYSTEM from making bad assumptions
Date
Msg-id 20190616174332.GR2480@tamriel.snowman.net
Whole thread Raw
In response to Re: [PATCH] Stop ALTER SYSTEM from making bad assumptions  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [PATCH] Stop ALTER SYSTEM from making bad assumptions
List pgsql-hackers
Greetings,

* Tom Lane (tgl@sss.pgh.pa.us) wrote:
> Stephen Frost <sfrost@snowman.net> writes:
> > Unless there's actually a use-case for duplicate entries in
> > postgresql.auto.conf,
>
> There isn't --- guc.c will just discard the earlier duplicates.

One might be able to argue for trying to create a stack or some such, to
allow you to more easily move between values or to see what the value
was set to at some point in the past, etc etc.  Until we see an actual
thought out use-case along those lines that requires supporting
duplicates in some fashion though, with code to make it all work, I
don't think we should allow it.

> > what we should do is clean them up (and possibly
> > throw a WARNING or similar at the user saying "something modified your
> > postgresql.auto.conf in an unexpected way").  I'd suggest we do that on
> > every ALTER SYSTEM call.
>
> +1 for having ALTER SYSTEM clean out duplicates.  Not sure whether
> a WARNING would seem too in-your-face.

I'd hope for a warning from basically every part of the system when it
detects, clearly, that a file was changed in a way that it shouldn't
have been.  If we don't throw a warning, then we're implying that it's
acceptable, but then cleaning up the duplicates, which seems pretty
confusing.

Thanks,

Stephen

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