Data feeds produce much of this source data, which come from Web server logs and outside sources. The Hadoop Flume component is used to ingest data. The Hadoop cluster also executes a series of MapReduce jobs to parse the raw data into summaries.

AOL also uses Couchbase's CouchDB as a switching station of sorts for data arriving from the feeds. Because CouchDB can work with data without writing it to disk, it can be used to parse data quickly before sending it to the next step.

"We didn't anticipate ad targeting to be a primary [market] for us. But Couchbase ended up filling a need for AOL and other ad companies," Ingenthron said. The work is "technically complex and has a lot challenges in processing data very quickly."

Scientific and medical publishing house Elsevier was looking for greater flexibility when it procured an XML-based, non-relational database system from Mark Logic, said Elsevier Labs Vice President Bradley Allen.

The scientific publishing world is moving from a static model to a more dynamic one, Allen explained. For the past few centuries, printed scientific paper, collected in journals, served as the basic unit of knowledge. It contained a description of the work, the authors and contributors, references and other core components of information. While the scientific publishing world is moving to digital, paper remains the dominant medium for data communication. "We're still in the horse-and-carriage era," Allen quipped.