If you think it's too complicated to implement that's fine with me. I just stumbled across this while trying to fix some failing tests.

My idea was to let a database dialect specify a character that denotes the start of a positional parameter. The default implementation would return '?'. The HANA dialect would override it to be '$'. The changes in the ParameterParser class shouldn't even be that big. Just another branch after checking for '?' that handles the database-specific character. However, I'm not sure about possible side effects of such a change. And I hadn't even thought about the documentation yet.