Worked on expanding the Velox backend in the apache/incubator-gluten repository by implementing support for basic arithmetic expressions under ANSI mode. Developed a configuration option that allows users to control fallback behavior, enabling direct execution of ANSI-mode arithmetic operations on Velox rather than defaulting to Spark. This approach improves execution predictability and reduces dependency on Spark for ANSI workloads. Added comprehensive tests to validate arithmetic operations under ANSI mode, ensuring correctness and reliability. Utilized Java and Scala for backend development, focusing on performance optimization and SQL processing. The work demonstrates depth in backend engineering and careful attention to execution paths and testing.