Have you thought about a "read at timestamp" construct in RethinkDB?

It's not really an MVCC thing, and you can work around it in data model, but for lots of reports (say, running in a cronjob), I want to run a query "as" the database saw things from at midnight UTC, even if i start running it at 2am? It would also make reports a more reproducible... but maybe this is really a datamodel problem. I felt when I read the Google Spanner papers that it was a pretty potentially useful feature for Read-Only queries.