iTunes App Store and an installment of one of the most successful gaming franchises in history both use Azure DocumentDB to ingest massive volumes of data and serve low latency queries to provide great user experiences. DocumentDB provides NoSQL service for highly available, globally distributed apps that want to take full advantage of SQL and JavaScript over document and key-value data without the hassles of on-premises or virtual machine-based cloud database options.
Azure DocumentDB guarantees less than 10 ms latencies on reads and less than 15 ms latencies on writes for at least 99% of requests. DocumentDB leverages a write-optimized, latch-free database engine designed for high-performance solid-state drives to run in the cloud at global scale. Read and write requests are always served from your local region while data can be distributed to other regions across the globe.
https://www.youtube.com/watch?v=joMY_JxNU4A