Re: IMMUTABLE and PARALLEL SAFE function markings

On Mon, Nov 26, 2018 at 7:47 PM Vik Fearing <vik(dot)fearing(at)2ndquadrant(dot)com> wrote:
> > I'm way less inclined to buy into the idea that it MUST be wrong, though.
> > Immutability is a promise about result stability and lack of side effects,
> > but it is not a promise about implementation details. There could be an
> > implementation reason not to run something in a parallel worker. Off the
> > top of my head, a possible example is "it's written in plfoo which hasn't
> > yet been made to work correctly in parallel workers".
>
> Now, see, that is an actual argument for making a difference. The other
> arguments in this thread were not, so say I.

I agree with you that Tom is the first person to make a real argument
for distinguishing these two things. And I think his argument is a
good one. I suspect that there are other cases too. I don't think
there are all that many cases, but I think they exist.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company