Hojjat Jafarpour

Thanks @mitch-seymour, I had a quick pass over the PR and the main issue at the moment is that we need to update the grammar in a way that the...

@dguy the change is more from the point of separating the parsing layer from the physical plan layer. Parser layer should be agnostic to the physical execution layer. The AST...

@big-andy-coates I don't think we need any engine specific wrapper for this. I know you prefer not to use `instance of` check so I changed it to switch using `WindowType`...

Thanks @mitch-seymour for the great write up! I'm going to second what @MichaelDrogalis mentioned on avoiding reload of functions for running queries. Indeed, I would go one step further and...