Re: WIP: Faster Expression Processing and Tuple Deforming (including JIT)

On Tue, Dec 6, 2016 at 1:56 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
>> I'm posting a quite massive series of WIP patches here, to get some
>> feedback.
>
> I guess the $64 question that has to be addressed here is whether we're
> prepared to accept LLVM as a run-time dependency. There are some reasons
> why we might not be:
>
> * The sheer mass of the dependency. What's the installed footprint of
> LLVM, versus a Postgres server? How hard is it to install from source?
>
> * How will we answer people who say they can't accept having a compiler
> installed on their production boxes for security reasons?
>
> * Are there any currently-interesting platforms that LLVM doesn't work
> for? (I'm worried about RISC-V as much as legacy systems.)

I think anything that requires LLVM -- or, for that matter, anything
that does JIT by any means -- has got to be optional. But I don't
think --with-llvm as a compile option is inherently problematic.
Also, I think this is probably a direction we need to go. I've heard
at least one and maybe several PGCon presentations about people JITing
tuple deformation and getting big speedups, and I'd like to finally
hear one from somebody who intends to integrate that into PostgreSQL.

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