I wanted to bring some attention and invite any comments on a PR [1] that is likely to merge soon and changes the DataFusion API (specifically how Exprs that represent a reference are handled).
While this is a large PR and will likely require changes from downstream consumers of DataFusion, I believe it is required for the proper support of multi-relation queries (i.e. JOINs etc). This PR is the result of the previous design work [2] that was previously discussed. Andrew [1] https://github.com/apache/arrow-datafusion/pull/55 [2] https://lists.apache.org/thread.html/r6b737b6368c4484ac74b01adda326d74d586861c63b218dae15d65e1%40%3Cdev.arrow.apache.org%3E
