We need to improve Projector class to get nested record fields, and we also add some language extension to specify certain nested records in table schema. Both works should be done together. Otherwise, we need to test an entire work process.
Using dot '.' would be good for the syntax to specify nested fields. Many systems (Hive, Google BigQuery, and Drill) already use this syntax. Probably, many users are familiar with this form.
For example, if employee is a root nested record field and it includes age and name fields, consisting two fields lastname and firstname, we can specify them individually as follows: