Key-value databases
With Azure Table storage (or just Azure tables), Microsoft also offers a key-value database. The Table API of Cosmos DB lets you write code against Cosmos DB as if it were a key-value database. This should facilitate the migration of Azure tables implementations to Cosmos DB. Azure tables have less functionality than Cosmos DB but are also cheaper. It is worth looking into key-value databases.
A key-value database stores data in values. Values can easily be retrieved using a key. It is comparable to a table with just two columns, a key column and a value column. The key is likely informative data by itself. The value is likely compound information.
Suppose you create an account on a website based on a key-value database. Your email address is used as the username. Your email address would be the key of the underlying key-value database. Using a hashing algorithm, the key determines the cluster node to store the data on. The value stores all the information...