  Online users are constantly seeking experiences, such as a hotel with clean
rooms and a lively bar, or a restaurant for a romantic rendezvous. However,
e-commerce search engines only support queries involving objective attributes
such as location, price, and cuisine, and any experiential data is relegated to
text reviews.
  In order to support experiential queries, a database system needs to model
subjective data and also be able to process queries where the user can express
varied subjective experiences in words chosen by the user, in addition to
specifying predicates involving objective attributes. This paper introduces
Opine, a subjective database system that addresses these challenges. We
introduce a data model for subjective databases. We describe how Opine
translates subjective queries against the subjective database schema, which is
done by matching the user query phrases to the underlying schema. We also show
how the experiential conditions specified by the user can be combined and the
results aggregated and ranked. We demonstrate that subjective databases satisfy
user needs more effectively and accurately than alternative techniques through
experiments with real data of hotel and restaurant reviews.
