Oracle-to-Postgres migration seems simple at first, but everything changes when you hit the DBMS_* packages. The 200,000 lines of procedural logic your application has built on Oracle’s built-in package ecosystem — job scheduling, optimizer statistics, transactional messaging, file I/O, and more — don’t migrate automatically, and no tool will tell you that until you’re already over budget. Replacing them means reconstructing decades of kernel-level behavior from scratch.
This guide covers which packages cause the most damage, what replacement actually looks like in practice, and how to build a migration plan with honest numbers in it.
Introduction: the common scenario I’ve