In August 2025, Kark focused on enhancing the reliability and correctness of the User-Defined Index (UDI) feature for partitioned indices in the facebook/rocksdb repository. Using C++ and leveraging expertise in database development and performance optimization, Kark addressed a critical bug that previously caused infinite loops during index block generation. The work involved refining the logic for writing meta blocks and strengthening UDI key handling across partitions, ensuring more predictable and stable behavior for users relying on partitioned indices. Through targeted unit testing and careful code improvements, Kark’s contributions reduced production risk and improved the overall robustness of UDI functionality.