Introduction to databases

Databases are systems that allow us to store and retrieve different types of data. Databases offer a variety of guarantees related to data storage, such as durability – a guarantee that all records and any related data changes will be persistent over time. A durability guarantee helps ensure that the data stored in a database won’t be lost in case of various events such as software and hardware restarts, which are pretty common for microservices

Databases help solve lots of different other problems related to data storage. Let’s illustrate one such problem using the metadata service that we created in Chapter 2. In our metadata service code, we implemented an in-memory repository for storing and retrieving the movie data that provides two functions, Get and Put. If we have just one instance of the metadata service, all its callers would be able to successfully write and read metadata records from the service memory, so long as a service...