The previous chapters covered what a relational database is, how the RDBMS implements the model, and how tables and keys are structured. This chapter covers the practical step that comes before you write your first SELECT: installing a database server and the client tools that connect to it. There are three open-source RDBMSs that dominate…
Every SQL statement belongs to a category. The category determines what the statement does, when it takes effect, and whether it can be rolled back. A CREATE TABLE is not the same kind of operation as an INSERT. A GRANT is not the same as a SELECT. The categories are not a matter of style…
You have seen the relational model and the software that implements it. This chapter is about the structure itself: the table, the row, the column, and the keys that connect them. These are the primitives that every SQL statement operates on. Every SELECT, every INSERT, every JOIN works because the table has columns, the columns…
You know what a relational database is: a collection of tables linked by keys. But a database is not a file that sits on disk and manages itself. Something must enforce the keys, validate the data types, process the queries, handle concurrent access from multiple users, and recover from crashes. That something is the Relational…
A relational database is a system for storing and managing data as a collection of tables that are linked to each other through shared values. This model was introduced by Edgar F. Codd at IBM in the 1970s, and it replaced the earlier “navigation” approach to data management with a more intuitive, data-centric one ….
The previous chapter covered the Kubernetes architecture. This chapter covers the tool you use to interact with that architecture: kubectl. It is the command-line interface for Kubernetes, and every action on the cluster goes through it . You use it to deploy applications, inspect resources, view logs, debug problems, and manage the cluster itself. The…
The previous chapter introduced Kubernetes and the declarative model. This chapter covers the architecture that makes the model work: the components that make decisions, the components that run workloads, and the resource that sits between them. Kubernetes has two halves. The control plane makes global decisions about the cluster and responds to cluster events ….
You have learned how to run a container. You can build an image, start a container, map a port, and view logs. That works on a single machine. But production is not a single machine. It is a fleet of servers, and the application must run across them, survive failures, scale with demand, and update…
The distinction between an image and a container is the foundation of everything Docker does. New users conflate the two, and the confusion persists until they hit a problem that forces them apart: an image that cannot be deleted because a container is using it, a container that loses data because the image is read-only,…
In the previous chapter, you learned what Docker is and how containers differ from virtual machines. This chapter puts that theory into practice. You will run your first container, understand exactly what happens at each step, and learn the commands that form the foundation of every Docker workflow. The LFCA exam places containers under DevOps…