In contrast to MySQL—which is a multi-thread database system—PostgreSQL is a multi-process database system. In multi-process systems you have a process tree with several processes that interact to share the work, but only a single thread for each process. Multi-process and multi-thread systems both have advantages and disadvantages, some of which are discussed in this post. Since PostgreSQL is a multi-process system, the focus will be on PostgreSQL and multi-process systems.
In this post you will see how to add a background worker to the extension and how to spawn new background workers.
This post assume that you’re familiar with C programming and also familiar with programming for Linux. In particular, you need to know about processes, signals, and sockets in Linux: what they are, how they work, and what they are used for.