Relational databases store data in relational tables, but sometimes the structure imposed by this model can be too rigid, and often leads to poor performance unless you spend time implementing detailed tuning. Other models, collectively known as NoSQL databases, exist. These models store data in other structures, such as documents, graphs, key-value stores, and column family stores. Azure Cosmos DB is a highly scalable cloud database service for NoSQL data. Which Azure Cosmos DB API should you use for data in key/value tables?