When evolving APIs, prioritize backward compatibility by creating new methods or overloads rather than modifying existing function signatures. This prevents breaking changes for existing users and extensions. Key strategies include: - Add new methods with descriptive names instead of changing existing ones (e.g., `duckdb_vector_slice_dictionary` instead of modifying `duckdb_slice_vector`) - Provide overloaded versions when adding parameters (e.g., separate `FileHandle::Read` methods with and without `QueryContext`) - Use proper memory management patterns in C APIs - allocate with `duckdb_malloc` so users can free with `duckdb_free`, or encapsulate complex data in opaque objects with accessor methods - Avoid overly specialized helper functions that may become maintenance burdens; instead expose existing lower-level APIs that provide the same functionality Example of good practice: ```cpp // Instead of modifying existing signature: // DUCKDB_C_API void duckdb_slice_vector(duckdb_vector vector, duckdb_selection_vector selection, idx_t len); // Add a new method: DUCKDB_C_API void duckdb_vector_slice_dictionary(duckdb_vector vector, idx_t dict_size, duckdb_selection_vector selection, idx_t len); ``` This approach ensures existing code continues to work while providing new functionality through clearly named, purpose-built interfaces.