Chapter 2. Server Architecture

In the previous chapter, we saw that starting a PostgreSQL cluster kicks off a few processes. The processes manage quite a bit of file I/O, manage other processes, and deal with memory allocation and a lot of other work. In this chapter, we will focus on the processes and their roles, memory management, and how they work together.

We will start by listing the processes once again. No client is connected to any of the databases yet:

[root@MyCentOS ~]# ps f -U postgres
  PID TTY      STAT   TIME COMMAND
 1918 tty1     S      0:00 /usr/local/pgsql/bin/postgres
 1920 ?        Ss     0:00  \_ postgres: checkpointer process   
 1921 ?        Ss     0:00  \_ postgres: writer process     
 1922 ?        Ss     0:00  \_ postgres: wal writer process   
 1923 ?        Ss     0:00  \_ postgres: autovacuum launcher process 
 1924 ?        Ss     0:00  \_ postgres: stats collector process