Andrew Chang enhanced memory governance in the facebook/rocksdb repository by enforcing strict block cache memory limits, focusing on stability under constrained workloads. He implemented logic in C++ to ensure that Get and MultiGet requests fail gracefully when the cache exceeds its defined capacity, preventing memory overuse and improving reliability. Andrew updated the MultiGet flow to respect the strict_capacity_limit option and developed comprehensive unit and integration tests to validate correct behavior under memory pressure. His work demonstrated depth in block cache optimization and memory management, addressing a critical bug and contributing to more predictable performance in memory-intensive environments.