pg_ctl is a postgresql command that created with potgresql software installation. you can start,stop and many other operations with pg_ctl. If you start postgresql with pg_ctl then postgresql cluster start normally and can run with no problems. with starting with pg_ctl you decided a manual start/stop. if you have operatig system service as postgesql-13.service the OS service do not informed about service start or stop. Because postgresql OS service executes /usr/lib/systemd/system/postgresql-13.service script actually and in this script there is not any control steps. Service script just control the data directories and then try to start a postmater process with controlled data directory. Therefore if postgresql was started with pg_ctl, trying OS “service start” fails. Below I will try to representive the stuation.
consequently, it is advised to use OS service. If you use OS service you can easly start and stop postgresql cluster after a reboot, without any intervention.
–psotgresql and OS service is down
[root@postgresstb data]# systemctl status postgresql-13.service
● postgresql-13.service - PostgreSQL 13 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-13.service; disabled; vendor preset: disabled)
Active: inactive (dead)
Docs: https://www.postgresql.org/docs/13/static/
[root@postgresstb data]# ps -ef | grep -i postmaster | grep -v grep
[root@postgresstb data]#
–start the postgresql cluster with pg_ctl
-bash-4.2$ /usr/pgsql-13/bin/pg_ctl start
waiting for server to start....2021-04-01 15:37:16.847 +03 [11628] LOG: redirecting log output to logging collector process
2021-04-01 15:37:16.847 +03 [11628] HINT: Future log output will appear in directory "log".
done
server started
-bash-4.2$ psql
psql (13.2)
Type "help" for help.
postgres=# \q
postgres 11670 11554 0 15:37 pts/0 00:00:00 grep --color=auto -i postmaster
-bash-4.2$ ps -ef | grep -i postgres
root 11552 1827 0 15:37 pts/0 00:00:00 su - postgres
postgres 11554 11552 0 15:37 pts/0 00:00:00 -bash
postgres 11628 1 0 15:37 ? 00:00:00 /usr/pgsql-13/bin/postgres
postgres 11629 11628 0 15:37 ? 00:00:00 postgres: logger
postgres 11631 11628 0 15:37 ? 00:00:00 postgres: checkpointer
postgres 11632 11628 0 15:37 ? 00:00:00 postgres: background writer
postgres 11633 11628 0 15:37 ? 00:00:00 postgres: walwriter
postgres 11634 11628 0 15:37 ? 00:00:00 postgres: autovacuum launcher
postgres 11635 11628 0 15:37 ? 00:00:00 postgres: stats collector
postgres 11636 11628 0 15:37 ? 00:00:00 postgres: logical replication launcher
postgres 11682 11554 0 15:37 pts/0 00:00:00 ps -ef
postgres 11683 11554 0 15:37 pts/0 00:00:00 grep --color=auto -i postgres
-bash-4.2$
–check the OS service
[root@postgresstb data]# systemctl status postgresql-13.service
● postgresql-13.service - PostgreSQL 13 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-13.service; disabled; vendor preset: disabled)
Active: inactive (dead)
Docs: https://www.postgresql.org/docs/13/static/
Apr 01 14:29:06 postgresstb postmaster[7485]: 2021-04-01 14:29:06.935 +03 ....
Apr 01 14:29:06 postgresstb systemd[1]: Started PostgreSQL 13 database server.
Apr 01 14:29:18 postgresstb systemd[1]: Stopping PostgreSQL 13 database se....
Apr 01 14:29:18 postgresstb systemd[1]: Stopped PostgreSQL 13 database server.
Apr 01 14:29:55 postgresstb systemd[1]: Starting PostgreSQL 13 database se....
Apr 01 14:29:56 postgresstb postmaster[7554]: 2021-04-01 14:29:56.033 +03 ...s
Apr 01 14:29:56 postgresstb postmaster[7554]: 2021-04-01 14:29:56.033 +03 ....
Apr 01 14:29:56 postgresstb systemd[1]: Started PostgreSQL 13 database server.
Apr 01 15:35:52 postgresstb systemd[1]: Stopping PostgreSQL 13 database se....
Apr 01 15:35:52 postgresstb systemd[1]: Stopped PostgreSQL 13 database server.
Hint: Some lines were ellipsized, use -l to show in full.
–start the postgresql OS service
[root@postgresstb data]# systemctl start postgresql-13.service
Job for postgresql-13.service failed because the control process exited with error code. See "systemctl status postgresql-13.service" and "journalctl -xe" for details.
[root@postgresstb data]# systemctl status postgresql-13.service
● postgresql-13.service - PostgreSQL 13 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-13.service; disabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Thu 2021-04-01 15:40:32 +03; 4s ago
Docs: https://www.postgresql.org/docs/13/static/
Process: 11853 ExecStart=/usr/pgsql-13/bin/postmaster -D ${PGDATA} (code=exited, status=1/FAILURE)
Process: 11847 ExecStartPre=/usr/pgsql-13/bin/postgresql-13-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
Main PID: 11853 (code=exited, status=1/FAILURE)
Apr 01 15:40:32 postgresstb systemd[1]: Starting PostgreSQL 13 database se....
Apr 01 15:40:32 postgresstb systemd[1]: postgresql-13.service: main proces...E
Apr 01 15:40:32 postgresstb systemd[1]: Failed to start PostgreSQL 13 data....
Apr 01 15:40:32 postgresstb systemd[1]: Unit postgresql-13.service entered....
Apr 01 15:40:32 postgresstb systemd[1]: postgresql-13.service failed.
Hint: Some lines were ellipsized, use -l to show in full.
–psotgresql OS service failed, but psotgresql cluster runnig. Now lets try to stop and restart postgaresql OS service.
[root@postgresstb data]# systemctl stop postgresql-13.service
[root@postgresstb data]# systemctl status postgresql-13.service
● postgresql-13.service - PostgreSQL 13 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-13.service; disabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Thu 2021-04-01 15:40:32 +03; 2min 30s ago
Docs: https://www.postgresql.org/docs/13/static/
Process: 11853 ExecStart=/usr/pgsql-13/bin/postmaster -D ${PGDATA} (code=exited, status=1/FAILURE)
Process: 11847 ExecStartPre=/usr/pgsql-13/bin/postgresql-13-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
Main PID: 11853 (code=exited, status=1/FAILURE)
Apr 01 15:40:32 postgresstb systemd[1]: Starting PostgreSQL 13 database server...
Apr 01 15:40:32 postgresstb systemd[1]: postgresql-13.service: main process exited, code=exited, status=1/FAILURE
Apr 01 15:40:32 postgresstb systemd[1]: Failed to start PostgreSQL 13 database server.
Apr 01 15:40:32 postgresstb systemd[1]: Unit postgresql-13.service entered failed state.
Apr 01 15:40:32 postgresstb systemd[1]: postgresql-13.service failed.
[root@postgresstb data]#
[root@postgresstb data]#
[root@postgresstb data]#
[root@postgresstb data]# systemctl restart postgresql-13.service
Job for postgresql-13.service failed because the control process exited with error code. See "systemctl status postgresql-13.service" and "journalctl -xe" for details.
[root@postgresstb data]#
[root@postgresstb data]#
[root@postgresstb data]# systemctl status postgresql-13.service
● postgresql-13.service - PostgreSQL 13 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-13.service; disabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Thu 2021-04-01 15:43:14 +03; 3s ago
Docs: https://www.postgresql.org/docs/13/static/
Process: 12015 ExecStart=/usr/pgsql-13/bin/postmaster -D ${PGDATA} (code=exited, status=1/FAILURE)
Process: 12009 ExecStartPre=/usr/pgsql-13/bin/postgresql-13-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
Main PID: 12015 (code=exited, status=1/FAILURE)
Apr 01 15:43:14 postgresstb systemd[1]: Starting PostgreSQL 13 database server...
Apr 01 15:43:14 postgresstb systemd[1]: postgresql-13.service: main process exited, code=exited, status=1/FAILURE
Apr 01 15:43:14 postgresstb systemd[1]: Failed to start PostgreSQL 13 database server.
Apr 01 15:43:14 postgresstb systemd[1]: Unit postgresql-13.service entered failed state.
Apr 01 15:43:14 postgresstb systemd[1]: postgresql-13.service failed.
[root@postgresstb data]#
[root@postgresstb data]#
[root@postgresstb data]#
–to resolve this problem we need to stop postgresql with pg_ctl and then start postgresql cluster with OS service.
[root@postgresstb data]# su - postgres
Last login: Thu Apr 1 15:37:08 +03 2021 on pts/0
-bash-4.2$ /usr/pgsql-13/bin/pg_ctl stop
waiting for server to shut down.... done
server stopped
-bash-4.2$ psql
psql: error: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
-bash-4.2$ logout
[root@postgresstb data]# systemctl status postgresql-13.service
● postgresql-13.service - PostgreSQL 13 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-13.service; disabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Thu 2021-04-01 15:44:42 +03; 49s ago
Docs: https://www.postgresql.org/docs/13/static/
Process: 12122 ExecStart=/usr/pgsql-13/bin/postmaster -D ${PGDATA} (code=exited, status=1/FAILURE)
Process: 12115 ExecStartPre=/usr/pgsql-13/bin/postgresql-13-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
Main PID: 12122 (code=exited, status=1/FAILURE)
Apr 01 15:44:42 postgresstb systemd[1]: Starting PostgreSQL 13 database server...
Apr 01 15:44:42 postgresstb systemd[1]: postgresql-13.service: main process exited, code=exited, status=1/FAILURE
Apr 01 15:44:42 postgresstb systemd[1]: Failed to start PostgreSQL 13 database server.
Apr 01 15:44:42 postgresstb systemd[1]: Unit postgresql-13.service entered failed state.
Apr 01 15:44:42 postgresstb systemd[1]: postgresql-13.service failed.
[root@postgresstb data]#
[root@postgresstb data]#
[root@postgresstb data]# systemctl start postgresql-13.service
[root@postgresstb data]#
[root@postgresstb data]# systemctl status postgresql-13.service
● postgresql-13.service - PostgreSQL 13 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-13.service; disabled; vendor preset: disabled)
Active: active (running) since Thu 2021-04-01 15:45:43 +03; 1s ago
Docs: https://www.postgresql.org/docs/13/static/
Process: 12274 ExecStartPre=/usr/pgsql-13/bin/postgresql-13-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
Main PID: 12280 (postmaster)
CGroup: /system.slice/postgresql-13.service
├─12280 /usr/pgsql-13/bin/postmaster -D /var/lib/pgsql/13/data/
├─12282 postgres: logger
├─12284 postgres: checkpointer
├─12285 postgres: background writer
├─12286 postgres: walwriter
├─12287 postgres: autovacuum launcher
├─12288 postgres: stats collector
└─12289 postgres: logical replication launcher
Apr 01 15:45:43 postgresstb systemd[1]: Starting PostgreSQL 13 database server...
Apr 01 15:45:43 postgresstb postmaster[12280]: 2021-04-01 15:45:43.133 +03 [12280] LOG: redirecting log output to logging collector process
Apr 01 15:45:43 postgresstb postmaster[12280]: 2021-04-01 15:45:43.133 +03 [12280] HINT: Future log output will appear in directory "log".
Apr 01 15:45:43 postgresstb systemd[1]: Started PostgreSQL 13 database server.
[root@postgresstb data]#
[root@postgresstb data]# su - postgres
Last login: Thu Apr 1 15:45:10 +03 2021 on pts/0
-bash-4.2$ psql
psql (13.2)
Type "help" for help.
postgres=# \q
-bash-4.2$ ps -ef | grep -i postgres
postgres 12280 1 0 15:45 ? 00:00:00 /usr/pgsql-13/bin/postmaster -D /var/lib/pgsql/13/data/
postgres 12282 12280 0 15:45 ? 00:00:00 postgres: logger
postgres 12284 12280 0 15:45 ? 00:00:00 postgres: checkpointer
postgres 12285 12280 0 15:45 ? 00:00:00 postgres: background writer
postgres 12286 12280 0 15:45 ? 00:00:00 postgres: walwriter
postgres 12287 12280 0 15:45 ? 00:00:00 postgres: autovacuum launcher
postgres 12288 12280 0 15:45 ? 00:00:00 postgres: stats collector
postgres 12289 12280 0 15:45 ? 00:00:00 postgres: logical replication launcher
root 12298 1827 0 15:45 pts/0 00:00:00 su - postgres
postgres 12299 12298 1 15:45 pts/0 00:00:00 -bash
postgres 12366 12299 0 15:45 pts/0 00:00:00 ps -ef
postgres 12367 12299 0 15:45 pts/0 00:00:00 grep --color=auto -i postgres
you can use pg_ctl still, but when you use pg_ctl OS service fails and the stuations above will accour again.
THE DATABASE DIARY 