po 8. 10. 2018 v 17:59 odesÃlatel Andres Freund <and...@anarazel.de> napsal:
> Hi, > > On 2018-10-08 11:43:42 -0400, Tom Lane wrote: > > Andres Freund <and...@anarazel.de> writes: > > > On October 8, 2018 8:03:56 AM PDT, Tom Lane <t...@sss.pgh.pa.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. > > Well, that'd then leave you with one more state (LLVM configured but not > installed, LLVM configured and installed, LLVM disabled and arguably > LLVM disabled but installed), but more importantly if you compile > without llvm enabled, you can still install a different extension that > would do JIT. You'd just have to set jit_provider = xyz, and it'd > work. If we made the generic JIT code depend on LLVM that'd end up > working pretty weirdly. I guess we could set jit_provider = '' > something if instead of hardcoding llvmjit if LLVM is disabled. > > > > 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.. > > That's not really the case, no. It controls whether the LLVM using jit > provider is built, not whether the generic JIT handling code is > available. Given that the generic code has no dependencies, there seems > little reason to do that differently? > I can accept this logic, but it looks very fragile. Can be there some safeguard against using wrong version or wrong API? > Greetings, > > Andres Freund >
