I've spent the last year using AWS DynamoDB at work. When we initially searched for a Scala client for DynamoDB, we had the following criteria:

• Good for Scala beginners
• Up to date
• Well documented

Sadly, none of the Scala libraries available at that time matched all three criteria. The most up-to-date libraries were not suitable for a team starting out with Scala and DynamoDB. The most beginner-friendly libraries were out-of-date, and most only had superficial documentation.

Cassandra Time-To-Live (TTL) is decribed in the Datastax documentation. This blog post briefly explores it to demonstrate that TTL is set per column, and not per row.

TTL Collections were introduced in MongoDB 2.2. You are now able to create an index which triggers the deletion of a document after the Time-To-Live (TTL) time passes.