The document discusses Blueflood, a system for processing simple metrics. It handles 120 million metrics per hour and 40 million Cassandra write operations per hour. It ingests metrics, performs rollups to aggregate data, and allows querying data. The system is scalable, processes metrics in real-time, and stores data in Cassandra for querying and rollups. It uses libraries for ingestion, rollups and querying and a scheduler to determine when to perform rollups.