Once we have installed pgpool, it is time to discuss the software architecture. From a user's point of view pgpool looks just like a normal database server and you can connect to it like to any other server:

pgpool will dispatch requests according to your needs.

Once you have understood the overall architecture as it is from a user's point of view, we can dig into a more detailed description:

When pgpool is started we fire up the pgpool parent process. This process will fork and create the so called child processes. These processes will be in charge of serving requests to end users and handle all the interaction with our database nodes. Each child process will handle a couple of pool connections. This strategy will reduce the number of authentication requests to PostgreSQL dramatically.

In addition to that we have the PCP infrastructure needed to handle configuration and management. We will discuss this infrastructure a little later in this chapter.

Finally we need a bunch of PostgreSQL database nodes as backend storage. End users will never connect to those nodes directly but always go through pgpool.