Key-value-stores and other non-relational databases are a hot topic right now, as it increasingly turns out that the traditional (= relational) approach is difficult to scale horizontally. In other words, it may be time — as Bob Ippolito put it — to “Drop ACID and think about data”.

If you couldn’t make it to the first “NoSQL Meetup Berlin” which recently took place at newthinking store — all the talks have been recorded and are on vimeo now:

• Consistency in Distributed Key/Value Stores, Monika Moser
  
• Redis — Fast and Furious, Mathias Meyer
  
• Peer to Peer Applications with CouchDB, Jan Lehnardt
  
• Riak, Martin Scholl
  
• MongoDB, Mathias Stearn
  
• 4th Generation Object Databases, Prof. Stefan Edlich
  

Heise has a good summary (in german).

Here at StudiVZ we are following this topic very closely and are actively investigating some of the alternatives. At the moment, Cassandra looks very promising to us.

Some more links:

• Quick Reference to Alternative data storages
• Comparing Key/Value Stores, Round 2
• NoSQL East 2009 – Summary of Day 1, Day 2