How to pass down custom expression to physical plan?

[another-s347]

Hello community!

I have a:

• Custom expression (UDF or operator) in SQL, which cannot be recognised without extension.
• Custom table provider, which can execute my custom expression.

Currently, I am using UDF to implement the expression, but it would be invoked directly instead of passing down to my table provider.

What's the appropriate way to do this?

Thanks

[alamb]

I suggest rewriting such expressions as a ScalarFunctionImpl - then the rest of datafusion will treat it just like any other UDF

In terms of converting your SQL to the function, perhaps you could use a custom expr planner:
https://docs.rs/datafusion/latest/datafusion/execution/trait.FunctionRegistry.html#method.register_expr_planner