For digital media company AOL, NoSQL products provide speed and volume that would not be possible using traditional relational databases.

The company uses Hadoop and the CouchDB NoSQL database to run its ad targeting operations, said Matt Ingenthron, manager of community relations for Couchbase, during another talk.

AOL has developed a system that can pick out a set of targeted ads for each time a user opens an AOL page. What ads are chosen can be based on the data that AOL has on the user, along with algorithmic guesses about what ads would be most of interest to that user. The process must be executed within about 40 milliseconds.

Source data is voluminous. Logs are kept on all users' actions on every server. They must be parsed and reassembled to build a profile of each user. The ad brokers also set a complex set of rules of how much they will pay for an ad impression, or what ads should be shown to which users.

This activity generates 4 to 5 terabytes of data a day, and AOL has amassed 600 petabytes of operational data. The system maintains more than 650 billion keys, including one for every user, as well as keys for handling other aspects of data as well. The system must react to 600,000 events every second.