As we discussed earlier, concurrent insertions aren't a concern for any table that uses UUIDs that are generated by the application or by Cassandra at row-creation time. Simply using UUIDs guarantees that we'll never have a row key collision.
Another scenario in which we can skip conditional inserts is when we have a globally unique natural key. For instance, if you're building a Rich Site Summary (RSS) reader, you might identify individual posts by their canonical URL. There's no concern about overwriting one post with another post's data because each row has a key that acts as a global unique identifier. In that case, you may choose to periodically update a local copy of the feed by downloading ...
