Really tough question. It depends on what you have on your DataTable. I haven't used that widget yet, but as written in Flutter documentation, its size depends on its children. So your struggle may comes from a widget inside your DataTable (I'm just guessing, as I have no access to your source code).

I this case, I don't know how these two widgets (DataTable + OverflowBar) behaves. Probably not very well, as OverflowBar needs parent constraints to define whether display its children as Row or Column...

So I think that finding and fixing the widget that creates your UI issue is a better solution.