I usually set my primary field as a formula, a concatenation of the Record_ID() and another field of the table, let’s say Name.
So if I have a table “Contact” with fields Name, Email, Status. I would use a concat of Name and record id as the primary field. This ensures that it’s unique. It also helps when I have a linked field to Contact from another table, as I am able to search based on Name.
How do you design so that Primary Field can be unique as well as easily searchable in the Linked Field popup?