Andrew Lamb

Thanks @ozankabak -- I will try and find time to review this later this week, though it may not be until the weekend

I took a brief look through this PR, and it looks quite cool -- will provide detailed comments later. For now I have started the CI checks

Thanks @metesynnada and @ozankabak -- I'll check this out more carefully tomorrow or Friday

I'll plan to merge this tomorrow unless I hear otherwise or anyone else would like longer to review. Thanks again @metesynnada and @ozankabak -- this looks epic

🚀 -- great first contribution

Maybe we could return a struct like ```rust enum NeededCoercion { /// cast inputs to these datatypes coerce_inputs: Vec, /// the resulting output will be this datatype output_type: DataType }...

I agree that type coercion doesn't really belong in an "optimizer" as it actually changes the meaning of the exprs (on purpose) where the other optimzier passes are supposed to...

> My plan is to do some refactor, and make good base for the next big refactor like the spark or other system. Sounds like a great plan to me

Here is a PR that contributes to this goal: https://github.com/apache/arrow-datafusion/pull/3728

I don't have a huge preference -- when in doubt I think we have tried to follow the postgres semantics, for consistency. In terms of checking for overflows, etc I...