This chapter focuses on processes. PostgreSQL uses processes to carry out all its magic. Database connections are handled by backend processes, while utility processes (such as vacuum, autovacuum, or WAL writer) run all the time to ensure that a database is in good shape.
From the user's perspective, the process-model provides strong isolation. This means that, apart from the database data being used as a communication stream, two processes cannot easily inter-communicate. For this reason, PostgreSQL provides a powerful and elegant model of event broadcasting that allows backend processes and client processes to synchronize and exchange data dynamically.
However, process communication is not the only feature shown in this chapter. PostgreSQL also allows the user to write custom processes, called background workers, that can...