How to add an integer unique id to query results - __efficiently__?

Question

Given a query, select * from ... (that might be part of CTAS statement)

The goal is to add an additional column, ID, where ID is a

Answer 1

If you are using Spark-sql your best bet would be to use the inbuilt function

monotonically_increasing_id

which generates unique random id in a separate column. And as you said you don't need it to be sequential so this should ideally suffice your requirement.