Is it more efficient to do SELECT and compare in Java or DELETE and INSERT

I am hitting a **REST API** to get data from a service. I transform this data and store it in a database. I will have to do this on some interval, 15 minutes, and then make sure this database has latest information. I am doing this in a Java program. I am wondering if it would be better, after I have queried all data, to do: 1. **SELECT** statements and compare vs transformed data and do **UPDATEs** (**DELETE** all associated records to what was changed and **INSERT** new) **OR** 2. **DELETE ALL** and **INSERT ALL** every time. Option 1 has potential to have a lot less transactions, guaranteed SELECT on all records because we are comparing, but potentially not a lot of UPDATEs since I don't expect data to be changing much. But it has downside of doing comparisons on all records to detect a change. I am planning on doing this using Spring Boot, JPA layer and possibly Postgres