Will it be ok to create "big" CDS views with thousands of fields from multiple tables / interface CDS views that should be used for ad-hoc reports in SE16x transactions?

Hi,I need to create a CDS view using UNION to get records from 2 tables, TAB1 and TAB2 like below.I do not want to have duplicate records with same key. So if records with same key exist in TAB1 and TAB2 it should take from TAB1. How should CDS view ...