China Eastern Airlines has successfully migrated its flight search platform from Oracle to MongoDB, achieving orders-of-magnitude performance improvements. To further improve customer experience and reduce costs, the airline implemented a new fare calculation engine built with Apache Spark and MongoDB, supporting over 1.6 billion queries per day and enabling the delivery of application features that had never before been possible. The new system pre-computes fares every night and loads them into an Apache Spark cluster, which calculates fares by applying business rules stored in MongoDB. The use of Apache Spark provides linear scalability and development simplicity for the engineering team, while MongoDB's flexible data model allows multiple fares to be stored for each route in a single document. The implementation has shown significant performance improvements, with a cluster of less than 20 servers required to meet the demands of 180 million fares and 1.6 billion daily searches.