The Network Assurance Engine team at Cisco Systems uses MongoDB as their time series database to analyze a large amount of network data, including 12 million time series data points generated every hour. To optimize performance and stay within a small resources footprint, they focused on optimizing their data model for time series data by making the timestamp part of their collection index and date partitioning the data. With these optimizations, they were able to analyze terabytes of time series data using MongoDB's flexibility and versatility in indexing data.