Worked on the MariaDB/server repository to enhance stability and correctness in query optimization for complex derived tables. Addressed a crash and 32-bit overflow that occurred during NATURAL JOIN operations when derived tables exceeded 64 columns by capping key generation to the handler’s max_key_parts, ensuring compatibility with Bitmap<64> capacity. Used C++ and SQL to implement the fix, which prevents the optimizer from creating invalid hash-join keys and eliminates a critical crash path in generate_derived_keys_for_table. Added regression tests to validate scenarios with more than 64 columns, improving the reliability of database internals and maintaining accurate optimizer behavior.