Just had a look (https://github.com/duckdb/duckdb/issues/9399). Yeah it's worrying that such a trivial query returned incorrect results - but credit to the Devs for getting it fixed quickly.
To my knowledge the only databases that can be described as "military-grade" in terms of testing are SQLite and Postgres.
To my knowledge the only databases that can be described as "military-grade" in terms of testing are SQLite and Postgres.