for example, according to https://www.reddit.com/r/Bitcoin/comments/3c7tma/any_thought...

Apache Cassandra is a database used by Facebook. It has converging databases. If you're used to normal SQL databases, it would be like a way of replicating information across lots of copies. Updates are done in really strange ways. Imagine a Facebook comment or status update. That gets a time associated with the data, and the database copies slowly converge to a common truth.

> gets a time associated with the data

it's easy to fake a timestamp in an untrusted network.

I don't think it can work under untrusted environment. But I'm not sure.