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

Hi,

On 2016-12-06 14:19:21 -0600, Nico Williams wrote:
> A bigger concern might be interface stability. IIRC the LLVM C/C++
> interfaces are not very stable, but bitcode is.

The C API is a lot more stable than the C++ bit, that's the primary
reason I ended up using it, despite the C++ docs being better.

> > I concur with your feeling that hand-rolled JIT is right out. But
>
> Yeah, that way lies maintenance madness.

I'm not quite that sure about that. I had a lot of fun doing some
hand-rolled x86 JITing. Not that is a ward against me being mad. But
more seriously: Manually doing a JIT gives you a lot faster compilation
times, which makes JIT applicable in a lot more situations.

> > I'm not sure that whatever performance gain we might get in this
> > direction is worth the costs.
>
> Byte-/bit-coding query plans then JITting them is very likely to improve
> performance significantly.

Note that what I'm proposing is a far cry away from that - this converts
two (peformance wise two, size wise one) significant subsystems, but far
from all the executors to be JIT able. I think there's some more low
hanging fruits (particularly aggregate transition functions), but
converting everything seems to hit the wrong spot in the
benefit/effort/maintainability triangle.

- Andres