Re: is JIT available

On Tue, 28 Jul 2020 at 15:55, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
>
> On Tue, 28 Jul 2020 at 15:33, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >
> > David Rowley <dgrowleyml(at)gmail(dot)com> writes:
> > > Maybe this would be better?
> >
> > > "returns true if jit is enabled and JIT compilation is available in
> > > this session (see Chapter 31)."
> >
> > The general, non-hacker meaning of "jit is enabled" would seem to
> > be pretty much what this function is already doing; and for that
> > matter, the same can be said for "JIT compilation is available".
> > We need something that's less tautological-looking. Maybe along
> > the lines of
> >
> > "returns true if a JIT compiler extension is available and the
> > <varname>jit</varname> parameter is set to <literal>on</literal>;
>
> That's probably better. FWIW, the "jit" is already a link to the GUC
> docs, so I had in mind that users would have known we meant "jit" the
> GUC rather than "jit" the feature. Your wording will help for anyone
> who thinks we're talking about the feature.
>
> > when this is true, JIT compilation will be performed."
>
> I'd probably drop this part since it's not really true. The query has
> to exceed the cost thresholds before that'll happen.

I pushed a doc change for this with slightly revised wording from what
you mentioned.

https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=d7c8576ebe3949a644c700a9f54d88e7e373a647

David