Hi folks,
We're using CalCite in our project for SQL parsing and validating. We have a question: is there any way to get all used columns from a SQL? Consider the following case: we have two tables `user` and `user_region`. And the SQL is like ``` SELECT id, name, age, country, province, city FROM user INNER JOIN user_region ON user.id = user_region.user_id WHERE age > 18; ``` The result will be a Map with two keys: * 'user' --> List('id', 'name', 'age') * 'user_region' --> List('country', 'province', 'city', 'user_id') ====== I've tried with SqlValidator (along with SqlValidatorScope, SqlValidatorNamespace) but found no easy ways to do this. I also tried to replay the validate process in our code but it seems impossible since most classes used are package private. [cid:e62a7598-728a-44d9-8e5c-365bdcde7c45] Could you please give us some suggestions? Thanks!