Процессы операционной системы

postgres$ ps -o pid,command --ppid `head -n 1 $PGDATA/postmaster.pid`
  PID COMMAND
 6241 postgres: checkpointer process   
 6242 postgres: writer process   
 6243 postgres: wal writer process   
 6244 postgres: autovacuum launcher process   
 6245 postgres: stats collector process   
 6246 postgres: bgworker: logical replication launcher   

К процессам, обслуживающим буферный кэш и журнал, можно отнести:

Остановка в режиме fast

postgres$ rm /home/postgres/logfile
postgres$ pg_ctl -w -l /home/postgres/logfile -D /usr/local/pgsql/data restart
waiting for server to shut down.... done
server stopped
waiting for server to start.... done
server started

Журнал сообщений сервера:

postgres$ cat /home/postgres/logfile
2018-12-24 17:28:19.662 MSK [6778] LOG:  listening on IPv4 address "0.0.0.0", port 5432
2018-12-24 17:28:19.662 MSK [6778] LOG:  listening on IPv6 address "::", port 5432
2018-12-24 17:28:19.664 MSK [6778] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5432"
2018-12-24 17:28:19.684 MSK [6779] LOG:  database system was shut down at 2018-12-24 17:28:19 MSK
2018-12-24 17:28:19.686 MSK [6778] LOG:  database system is ready to accept connections

Остановка в режиме immediate

postgres$ rm /home/postgres/logfile
postgres$ pg_ctl -w -l /home/postgres/logfile -D /usr/local/pgsql/data restart -m immediate
waiting for server to shut down.... done
server stopped
waiting for server to start.... done
server started

Журнал сообщений сервера:

postgres$ cat /home/postgres/logfile
2018-12-24 17:28:19.955 MSK [6824] LOG:  listening on IPv4 address "0.0.0.0", port 5432
2018-12-24 17:28:19.955 MSK [6824] LOG:  listening on IPv6 address "::", port 5432
2018-12-24 17:28:19.957 MSK [6824] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5432"
2018-12-24 17:28:19.977 MSK [6825] LOG:  database system was interrupted; last known up at 2018-12-24 17:28:19 MSK
2018-12-24 17:28:20.217 MSK [6825] LOG:  database system was not properly shut down; automatic recovery in progress
2018-12-24 17:28:20.219 MSK [6825] LOG:  invalid record length at 0/17AD8BC: wanted 24, got 0
2018-12-24 17:28:20.219 MSK [6825] LOG:  redo is not required
2018-12-24 17:28:20.227 MSK [6824] LOG:  database system is ready to accept connections

Перед тем, как начать принимать соединения, СУБД выполнила восстановление (automatic recovery in progress).