Re: JIT compiling with LLVM v9.0

Hi,

On 2018-01-31 11:53:25 -0500, Robert Haas wrote:
> On Wed, Jan 31, 2018 at 10:22 AM, Peter Eisentraut
> <peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:
> > On 1/30/18 21:55, Andres Freund wrote:
> >> I'm open to changing my mind on it, but it seems a bit weird that a
> >> feature that relies on a shlib being installed magically turns itself on
> >> if avaible. And leaving that angle aside, ISTM, that it's a complex
> >> enough feature that it should be opt-in the first release... Think we
> >> roughly did that right for e.g. parallellism.
> >
> > That sounds reasonable, for both of those reasons.
>
> The first one is a problem that's not going to go away. If the
> problem of JIT being enabled "magically" is something we're concerned
> about, we need to figure out a good solution, not just disable the
> feature by default.

That's a fair argument, and I don't really have a good answer to it. We
could have a jit = off/try/on, and use that to signal things? I.e. it
can be set to try (possibly default in version + 1), and things will
work if it's not installed, but if set to on it'll refuse to work if not
enabled. Similar to how huge pages work now.

Greetings,

Andres Freund