Java Engineer – Application / Database Modernization

Mactores is the agent-native AWS modernization firm. Most modernization work doesn't ship, it stalls in pilots, slips a year, or lands at three times the budget. We exist to ship it: production systems running, legacy retired, outcomes measured. Our delivery is built on Aedeon, the agent platform built by Mactores ' founders' sister company, which absorbs the repetitive 60–70% of engagement work, discovery, dependency mapping, validation, test generation, that traditional consulting bills human hours against. Forward-deployed engineers own the rest: architecture, judgment, and cutover, on dates we commit to in the contract. Enterprises stuck on Oracle carry license renewals, vendor-specific SQL nobody wants to touch, and application layers welded to the database underneath them. This role sits in our Application & Database Modernization pillar: you'll work an Oracle-to-PostgreSQL migration where Aedeon handles the mechanical conversion at scale and you own what the tools can't the refactoring judgment inside large enterprise Java codebases. You'll rewrite the SQL the application actually depends on, align it with the modernized schema, prove functional parity, and see the application through production cutover. Not a proof of concept. A system that ships. What you will do? Analyze and remediate large enterprise Java codebases — replace legacy and database-specific SQL constructs with modern, standards-compliant SQL. Convert embedded SQL in Java services and MyBatis XML mappers: rewrite vendor-specific functions, sequences, pagination logic, dynamic SQL, and error-handling patterns. Work closely with schema and database migration engineers so application-layer SQL lands aligned with the modernized target schema. Refactor Java transaction logic, error handling, drivers, and ORM/DAO layers to match the behavior of modern databases. Run unit, integration, and performance testing to confirm functional parity and hit performance SLAs post-modernization. Support production