[crote]

I'm not familiar with the library either, but that seems to be a SQL expression executed on the database server. It's basically a copy-paste from the official documentation[0]. So no, not a lambda expression, because it's not computed in Python.

As to the extra parentheses: I bet that's a force-of-habit thing to prevent potential issues. For example, it seems Sqlite requires them for exactly this kind of default definition[1]. It could also read to nasty bugs when the lack of parentheses in the resulting SQL could result in a different parse than expected[2]. Adding them just-to-be-safe isn't the worst thing to do.

[0]: https://docs.sqlalchemy.org/en/13/core/metadata.html

[1]: https://github.com/sqlalchemy/sqlalchemy/issues/4474

[2]: https://github.com/sqlalchemy/sqlalchemy/issues/5344

[nikonyrh]

Aah that makes sense, thanks!