Traackr’s original model included three distinct data buckets: 1) Influencers, 2) Channels (sites for published content), and 3) Posts (tweets, blogs, etc.). Traackr creates influencer listings based on mining these data sets for keywords. If the information was only loosely coupled or if the wrong type of relationship festered for too long, inaccurate, inconsistent influencer rankings would result. In order to provide higher quality lists to clients, Traackr needed to build stronger associations within their data model, and HBase lacked indexing and ad-hoc querying capabilities to make this happen.
A few other MongoDB features are mentioned in the post, but the key is indexing and ad-hoc queries.
Original title and link: MongoDB at Traackr: Indexing and Ad-Hoc Querying (NoSQL database©myNoSQL)