DBLens Collaborative Filtering Research Engine

SourceForge DBLens Page (to download DBLens)

[October 10th, 2003] If you are looking for freely available collaborative filtering recommendation engine, I recommend that you consider the CFEngine instead. The CFEngine is my latest recommender engine, this time written in Java. The CFEngine supports high-performance operation, is much more stable, and much better supported. We are also actively developing the CFEngine, while development on DBLens has ceased. You can download CFEngine from


DBLens is a Oracle-based toolkit for performing collaborative filtering. DBLens is a collection of PL/SQL code and accompanying shell scripts that provides a flexible and efficient method for performing collaborative filtering. The system was designed to perform primarily batch offline computation. The parameters of the computation are highly configurable. Currently the system takes data in the form of numerical ratings of the form:

<userid, itemid, numeric rating> Given a set of ratings and a request for a prediction <userid, itemid, ?> the system will locate users with similar interests, and use their ratings to predict the unknown rating. There are also procedures for producing the top-n highest predicted items for a given user, although these are not thoroughly tested. DBLens does all of it's computation inside Oracle using PL/SQL, and thus an installation of Oracle on Unix is a necessity. DBLens has been tested on Solaris, but should run on any Unix for which Oracle is available.

Intended Audience

DBLens was designed as a tool for research into collaborative filtering algorithms. Therefore the intended audience is people doing research into collaborative filtering and information filtering. The system was designed for batch usage, although DBLens can produce predictions in real time - just not in volume.

License to Use

DBLens is released under a license very similar to that of BSD Unix. Basically, you can use this software for just about anything, as long as you maintain the copyright notices. See the licenses in the source files for more information.

Who is responsible?

DBLens was primarily developed by When initially developed, both were members of the GroupLens Research Group at the University of Minnesota.

Downloading DBLens

You can download DBLens from SourceForge.

Open Source Development

DBLens has been "Open Sourced." If you would like to contribute code or modifications, please contact Jon Herlocker. The CVS source code tree is available through SourceForge.

Educational Licenses for Oracle

Don't despair! While commercial licenses cost big $$$, Oracle will license its Oracle server product to educational institutions for a reasonable sum of money (several hundred dollars).

Publicly Available Data

If you are looking to do some CF research, the next thing you will probably need after getting DBLens is a dataset. GroupLens Research has a set publicly available, consisting of 100,000 ratings for 1682 movies by 943 users.

GroupLens Research

                           Logo Questions or comments? Contact Jon Herlocker.