Which scenarios are suitable use cases for Alibaba Cloud's MongoDB service?

The choice indicating that applications requiring high queries per second (QPS) are suitable use cases for Alibaba Cloud's MongoDB service is accurate because MongoDB is designed to handle high-volume and high-velocity data interactions effectively.

MongoDB is a NoSQL database that allows for horizontal scaling, making it capable of managing a large number of read and write operations without compromising performance. This is particularly useful in scenarios such as logging applications, where the ability to quickly process and store large amounts of data concurrently is crucial. Its document-oriented structure allows for fast data access and retrieval, thus supporting applications that require high throughput.

Applications that do not need a flexible schema are generally not ideal for MongoDB, as one of the significant advantages of this database is its ability to handle a variety of data types and structures seamlessly. Similarly, applications that are best suited for relational databases would typically benefit from the relational features that MongoDB may not provide, particularly in terms of enforcing strict data integrity and relational structures. Lastly, while MongoDB does support some transactional capabilities, basic transactional support is often a more straightforward requirement better suited for traditional relational databases rather than the more complex capabilities of MongoDB that excel in distributed systems.