Re: PostgreSQL 12, JIT defaults

Andres Freund <andres(at)anarazel(dot)de> writes:
> On October 8, 2018 8:03:56 AM PDT, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> A look in guc.c shows that jit defaults to "on" whether or not JIT is
>> enabled at compile time.
>> This seems, at best, rather user-unfriendly.
>> And it's not like our conventions for other compile-option-affected
>> GUCs, eg the SSL ones.

> That was intentional, even though it perhaps should be better documented. That allows a distro to build and distribute pg without llvm enabled, but then have the JIT package with all the dependencies separately. The pg yum packages do so.

I'm not following. A distro wishing to do that would configure
--with-llvm, not without, and then simply split up the build results
so that the JIT stuff is in a separate subpackage. If you configured
--without-llvm then the resulting core code is (one hopes) entirely
incapable of using JIT, and it'd be better if the GUC settings
reflected that.

regards, tom lane