What Is the Job of the War Writer?

Creating a listener on the backend application that accepts connections is simple. You listen on an address-port pair, connection attempts to that address and port will get added to an accept queue; The application accepts connections from the queue and start reading the data stream sent on the connection.

However, what part of your application does the accepting and what part does the reading and what part does the execution? You can architect your application in many ways based on your use cases. I have a medium post just exploring the different options.

In this video I explore the PostgreSQL process architecture in details. Please note that the information here is derived from both the Postgres doc and code. Discussions about scalability and performance are solely based on my opinions.

0:00 Intro

1:30 Overview

3:30 Postgres MVCC

5:30 Processes vs Threads

7:40 Postmaster Process

8:00 Backend Processes

13:30 Shared Buffers

14:52 Background Workers

17:18 Auxiliary Processes

17:45 Background Writer

22:30 Checkpointer

23:40 Logger

24:06 Autovacuum Launcher and Workers

25:30 WAL Processes

28:53 Startup Process

Read full article

https://medium.com/@hnasr/postgresql-process-architecture-f21e16459907