Hi,
I'm interested in using user defined table functions for regular schemed
tables, that exist on my `CatalogReader`.
I'm currently using Calcite 1.38, and the behavior I'm looking for is
something like:
```
select * from f(t) | select * from table(f(t)) | select * from table (f
(table t)) | select * from f(t.*)
```
where `f` is some table function.
basically, anything that enables me to create a `RelNode` that takes a
table (or a rowtype of the table's columns) as it's input and return
something similar, depending on the table functions.
Is there some known or used way for me to try? If I understood
correctly, table functions takes constant tables, but I hope that I'm
mistaken, and there are some other ways to use it.
