Andrew Chang enhanced memory governance in the facebook/rocksdb repository by enforcing strict block cache memory limits during Get and MultiGet operations. He implemented logic in C++ to ensure that requests fail gracefully when the cache exceeds its defined capacity, improving system reliability under memory pressure. Andrew updated the MultiGet flow to respect the strict_capacity_limit option and developed comprehensive unit and integration tests to validate correct behavior under constrained conditions. His work focused on block cache optimization and memory management, addressing a critical bug and contributing to more predictable RocksDB performance in environments with tight memory requirements.