On Fri, 22 May 2020 at 12:12, Andy Fan <zhihui.fan1...@gmail.com> wrote: > Actually I am not sure about what does the "parameterized sub plan" mean (I > treat is a SubPlan Node), so please correct me if I misunderstand you:) > Because > the inner plan in nest loop not a SubPlan node actually. so if bind the > facility to SubPlan node, we may loss the chances for nest loop.
A parameterized subplan would be a subquery that contains column reference to a query above its own level. The executor changes that column reference into a parameter and the subquery will need to be rescanned each time the parameter's value changes. > And when we > consider the usage for nest loop, we can consider the below example, where > this > feature will be more powerful. I didn't quite get the LATERAL support quite done in the version I sent. For now, I'm not considering adding a Result Cache node if there are lateral vars in any location other than the inner side of the nested loop join. I think it'll just be a few lines to make it work though. I wanted to get some feedback before going to too much more trouble to make all cases work. I've now added this patch to the first commitfest of PG14. David
