Worked on the Shopify/rails repository to deliver a feature enabling composite primary keys on join tables created with create_join_table, addressing PostgreSQL logical replication requirements. The implementation introduced a primary_key option, allowing developers to specify keys such as [:assembly_id, :part_id] while maintaining backward compatibility by preserving the default behavior. This change streamlined database setup and improved data integrity for join-table patterns without altering existing APIs. The work demonstrated proficiency in Ruby on Rails, back-end development, and database design, integrating primary key configuration seamlessly into Rails migrations to support more robust and flexible relational data models in production environments.