rudb-compat

rudb-compat is a comprehensive testing harness designed to verify the compatibility of the rudb database with DuckDB. It transforms compatibility claims into measurable data by running differential executions against a real DuckDB binary. The suite evaluates conformance across four distinct levels: data compatibility (storage format fidelity), query compatibility (SQL dialect coverage), API compatibility (C ABI adherence), and ecosystem compatibility (extensions and wire protocol). Key features include: - **Differential Execution**: Compares results from rudb and DuckDB on identical queries to ensure behavioral parity. - **Weighted Coverage**: Uses usage-weighted metrics rather than simple code coverage to assess SQL function and statement support. - **Automated Bisecting**: Automatically reduces and bisects failing queries to identify specific optimizer passes or logic errors causing discrepancies. - **Corpus Integration**: Runs against DuckDB's official `sqllogictest` corpus, ClickBench benchmarks, and generated/metamorphic queries to find edge cases. - **Strict Version Control**: Ensures comparisons are made against a pinned DuckDB commit hash, not just version strings, to avoid drift. The tool is intended for developers maintaining rudb to track progress toward full DuckDB compatibility and for users verifying migration safety. It operates as a separate repository to maintain independence from the main implementation and to allow trustless verification.