Would it be possible to know which article was number one million?

I don't think it is possible to establish this after the fact.

Let us say article x on p: was the millionth article and was added at time t. Parsing the databases at time t+10min another article y would seem the millionth article because someone had deleted some articles in the meantime on q:

And so on, every measurement would point to a different article.

Erik Zachte