Re: JIT compiling with LLVM v9.0

On Thursday, January 25, 2018 8:02:54 AM CET Andres Freund wrote:
> Hi!
>
> On 2018-01-24 22:51:36 -0800, Jeff Davis wrote:
> > Can we store the bitcode in pg_proc, simplifying deployment and
> > allowing extensions to travel over replication?
>
> Yes, we could. You'd need to be a bit careful that all the machines have
> similar-ish cpu generations or compile with defensive settings, but that
> seems okay.

Hi

Doing this would 'bind' the database to the LLVM release used. LLVM can, as
far as I know, generate bitcode only for the current version, and will only be
able to read bitcode from previous versions. So you can't have, for instance a
master server with LLVM 5 and a standby server with LLVM 4.
So maybe PostgreSQL would have to expose what LLVM version is currently used ?
Or a major PostgreSQL release could accept only one major LLVM release, as was
suggested in another thread ?

Pierre