Going schema-less

In the previous sections, the focus was on relational databases, where strict schemas are applied to every table. A completely different approach to database schema management is to let go of having a database schema altogether. This can be done by using schema-less or document databases. A well-known example of a schema-less database is Azure Cosmos DB. These databases can store documents of different forms in the same “table.” Table is in quote marks here since these types of databases often do not use the term “table,” but call this a database, a container, or a collection.

Since these databases can store documents with a different schema in the same collection, schema changes no longer exist from a database’s point of view. But of course, there will be changes to the structure of the corresponding objects in the application code over time. To see how to handle this, it is best to differentiate between storing objects in the...