The document discusses Macy's use of real-time recommender systems using Apache Kiji. Macy's Advanced Analytics team builds predictive models to recommend complementary products to customers on their website. They use a Hadoop/NoSQL approach to access raw data and build models near the data. Their models are deployed using Apache Kiji, which provides scalable real-time scoring and decisions. Kiji allows quick development and real-time updates of recommender models to improve customer acquisition and retention.