This is a wonderful project that will keep your team occupied for a long time, perhaps until retirement! Congratulations!

Seriously, I foresee big problems whose causes are not the technology but the ideas behind the technology. Without looking at the code, I suspect the pro*c solutions were written by data-centric programmers who had learned how to deal with databases. Spring batch is part of the Spring framework, written in Java by programmers who think processing should be done outside the database.

Data-intensive processing should be done as close to the data as possible, especially if the database is an expensive, high-quality product. That means leveraging SQL itself as much as possible and driving SQL through PL/SQL in jobs scheduled in the database.

Personally, I know of a spring batch job that took 8 VMs (7 Java and 1 Oracle) and several hours to insert 8 million rows. The Java experts got the time down to one hour.

I got the time down to 25 minutes using 1 VM (Oracle). This was without parallelism so 1 CPU. SQL and PL/SQL.

By the way, generating test data for the same project took up to a week. I got it down to a few hours. SQL and PL/SQL.

So here are your alternatives:
1) Dogmatic managers / architects: either go with the flow and watch the project fail or be the voice crying in the wilderness.
2) Reactive management: let the project start to fail and come in as the savior at the right moment.
3) Proactive management: propose a test phase comparing two approaches based on objective criteria agreed in advance.

Enjoy!

Best regards,
Stew Ashton