Re: Custom Scan APIs (Re: Custom Plan node)

KaiGai,

* Kohei KaiGai (kaigai(at)kaigai(dot)gr(dot)jp) wrote:
> BTW, this kind of discussion looks like a talk with a ghost because
> we cannot see the new interface according to the parallel execution
> right now, so we cannot have tangible investigation whether it becomes
> really serious backward incompatibility, or not.

Yeah, it would certainly be nice if we had all of the answers up-front.
What I keep hoping for is that someone who has been working on this area
(eg: Robert) would speak up...

> My bet is minor one. I cannot imagine plan-node interface that does
> not support existing non-parallel SeqScan or NestLoop and so on.

Sure you can- because once we change the interface, we're probably going
to go through and make everything use the new one rather than have to
special-case things. That's more-or-less exactly my point here because
having an external hook like CustomScan would make that kind of
wholesale change more difficult.

That does *not* mean I'm against using GPUs and GPU optimizations. What
it means is that I'd rather see that done in core, which would allow us
to simply change that interface along with the rest when doing wholesale
changes and not have to worry about backwards compatibility and breaking
other people's code.

Thanks,

Stephen