Re: plpgsql.consistent_into

2014/1/12 Florian Pflug <fgp(at)phlo(dot)org>

> On Jan12, 2014, at 22:37 , Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> > There is GUC for variable_conflict already too. In this case I would to
> > enable this functionality everywhere (it is tool how to simply eliminate
> > some kind of strange bugs) so it needs a GUC.
> >
> > We have GUC for plpgsql.variable_conflict three years and I don't know
> > about any problem.
>
> I must say I hate behaviour-changing GUCs with quite some passion. IMHO
> they tend to cause bugs, not avoid them, in the long run. The pattern
> usually is
>
> 1) Code gets written, depends on some particular set of settings
> to work correctly
>
> 2) Code gets reused, with little further testing since it's supposed
> to be battle-proven anyway. Settings get dropped.
>
> 3) Code blows up for those corner-cases where the setting actually
> matter. Debugging is hell, because you effectively have to go
> over the code line-by-line and check if it might be affected by
> some GUC or another.
>
> Only a few days ago I spent more than an hour tracking down a bug
> which, as it turned out, was caused by a regex which subtly changed its
> meaning depending on whether standard_conforming_strings is on or off.
>
> Some GUCs are unavoidable - standard_conforming_strings, for example
> probably still was a good idea, since the alternative would have been
> to stick with the historical, non-standard behaviour forever.
>
> But in this case, my feeling is that the trouble such a GUC may cause
> out-weights the potential benefits. I'm all for having a directive like
> #consistent_into (though I feel that the name could convey the
> meaning better). If we *really* think that this ought to be the default
> from 9.4 onward, then we should
>
> *) Change it to always complain, except if the function explictly
> specifies "#consistent_into on" or whatever.
>
> *) Have pg_dump add that to all plpgsql functions if the server
> version is < 9.4 or whatever major release this ends up in
>

I disagree - automatic code injection can is strange. Is not problem inject
code from simple DO statement, but I dislike append lines to source code
without any specific user request.

Maybe this problem with GUC can be solved in 9.4. Some specific GUC can be
ported with database.

Pavel

>
> That's all just my opinion of course.
>
> best regards,
> Florian Pflug
>
>