Code in Application or the database?

My employer has a fairly large Delphi application with ~5 Million lines of pascal code.

They have a large database and use Oracle 12c to manage it.

I have seen many methodologies on how to manage your database access code.
On the edges I see two extremes are:

• Do everything in Stored Procedures 
• Do everything in Code outside the database, (Typical ORM)

I believe you need to use the best tool for the job.   So sometimes we are doing massive amounts of data processing that never leaves the database.     For that I use Packages/Stored Procedures in Oracle.     

Years ago we had a process that was 100% in code, and it took 20+ hours in code to execute, due to the round trips to the database.   When we looked at optimization, it was clear that network time was a huge part of the equation.    This Delphi process was converted to Oracle PL/SQL and was further optimized and our time was was reduced to <30 minutes

A simple example using the best tool for the job.    I have been a advocate of unit testing in Delphi.    Several months ago we had do some major PL/SQL work that resulted in about 50k lines of PL/SQL code.     Way too many lines of code to write and trust without sometime of unit testing framework.    We had been testing PL/SQL code from Delphi using DUnitX, but it was one too many steps away from the code under test.    I started working with utPLSQL a user testing framework for PL/SQL.   

In the past few weeks: I finished the move of utPLSQL from SourceForge to GitHub, and have released version 2.3.1 of utPLSQL.

Still love and use DUnitX but I use it from my Delphi Code not my PL/SQL code.

Regardless of the technology you find yourself using for development you need to unit test.