Re: [bug?] Missed parallel safety checks, and wrong parallel safety

On Fri, Apr 23, 2021 at 6:45 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Greg Nancarrow <gregn4422(at)gmail(dot)com> writes:
> > I'm curious. The FmgrBuiltin struct includes the "strict" flag, so
> > that would "lock down the value" of the strict flag, wouldn't it?
>
> It does, but that's much more directly a property of the function's
> C code than parallel-safety is.
>

Isn't parallel safety also the C code property? I mean unless someone
changes the built-in function code, changing that property would be
dangerous. The other thing is even if a user is allowed to change one
function's property, how will they know which other functions are
called by that function and whether they are parallel-safe or not. For
example, say if the user wants to change the parallel safe property of
a built-in function brin_summarize_new_values, unless she changes its
code and the functions called by it like brin_summarize_range, it
would be dangerous. So, isn't it better to disallow changing parallel
safety for built-in functions?

Also, if the strict property of built-in functions is fixed
internally, why we allow users to change it and is that of any help?

--
With Regards,
Amit Kapila.