Worked on the sequelize/sequelize repository to enhance the reliability and performance of ORM-generated SQL queries. Focused on backend development and database query optimization using JavaScript and TypeScript, the work addressed a bug where index hints were incorrectly applied to associated tables in complex join scenarios. By refining the core logic, index hints were limited to the top-level table, preventing suboptimal query plans and potential performance issues. Added regression tests ensured ongoing correctness and stability. This targeted fix improved query planning and execution, delivering more predictable performance for applications relying on Sequelize’s ORM capabilities in demanding database environments.