{"id":628,"date":"2023-10-01T13:07:34","date_gmt":"2023-10-01T10:07:34","guid":{"rendered":"http:\/\/pgdataeraold.local\/?p=628"},"modified":"2023-10-01T13:07:34","modified_gmt":"2023-10-01T10:07:34","slug":"starting-and-stopping-postgresql-instance","status":"publish","type":"post","link":"https:\/\/pgdataera.com\/en\/starting-and-stopping-postgresql-instance\/","title":{"rendered":"Starting and Stopping Postgresql Instance"},"content":{"rendered":"\n

Starting Postgresql Instance<\/h2>\n\n\n
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\"\"<\/figure><\/div>\n\n\n
\n\n\n\n

If installed from pre-built packages (yum\/apt install postgresql\u2026), services are
created according to the operating system. Thus, it can be stopped and started with
systemctl commands and its startup can be automated (systemctl enable
postgres).<\/p>\n\n\n\n

Note: In the appendix chapters, where the installation and architecture from the prebuilt
package were explained, and in the first chapter, you can examine the installation
example from the source code. (to access the installation from the source kod –><\/a> <\/mark><\/strong>)<\/p>\n\n\n\n

Cluster (data directory)<\/td>\/pg\/data\/13.6<\/td><\/tr>
Binary location<\/td>\/pg\/home\/13.6\/bin<\/td><\/tr>
Port (changed due to other instance)<\/td>5434<\/td><\/tr><\/tbody><\/table>
The database to be used in the examples is built from the source code. Directory information is as table.<\/figcaption><\/figure>\n\n\n\n
\n\n\n\n
# The following lines can be added to the bottom of the .profile\nfile in order repeat the full path every time.\n\nvim \/var\/lib\/postgresql\/.profile\nexport PGDATA=\/pg\/data\/13.6\nexport PGDATABASE=postgres\nexport PGUSER=postgres\nexport PGPORT=5434\nexport PATH=\/pg\/home\/13.6\/bin:$PATH\n\n# In order to enable the current variables in the current session.\nsource ~\/.profile\n\n# To check.\npostgres@srv1:~$ which postgres\n\/pg\/home\/13.6\/bin\/postgres<\/pre>\n\n\n\n
\n\n\n\n
The following commands are executed to start the database.<\/p>\n\n\n\n
postgres@srv1:~$ postgres -D \/pg\/data\/13.6\/\nLOG:starting PostgreSQL 13.6 on x86_64-pc-linux-gnu,compiled by\ngcc (Debian 8.3.0-6)8.3.0,64-bit\n[9860] LOG: listening on IPv4 address \u201c0.0.0.0\u201d, port 5434\n[9860] LOG: listening on IPv6 address \u201c::\u201d, port 5434\n[9860] LOG: listening on Unix socket \u201c\/tmp\/.s.PGSQL.5434\u201d\n[9861] LOG: database system was shut down at 16:13:34 +03\n[9860] LOG: database system is ready to accept connections<\/pre>\n\n\n\n
\n\n\n\n
Note: In this way, the postgresql instance runs in the foreground. If the SSH session is
terminated, the database is also closed.
If PGDATA is defined in environment variables, \u201c\u2013D\u201d parameter is not required.<\/p>\n\n\n\n
In this manner, stdout and sterr will be directed to the log\nfile by running in the background.\n\npostgres -D \/pg\/data\/13.6\/ > postgresql.log 2>&1 &\n\n# To run in debug mode (-d 5), should be used with caution as\nlog file grows very quickly.\n\npostgres -D \/pg\/data\/13.6\/ -d 5 > debugpostgres.log 2>&1 &<\/pre>\n\n\n\n
\n\n\n\n
postgres :<\/strong><\/code> It can take many parameters, there are details on man postgres or postgresql.org.<\/p>\n\n\n\n
pg_ctl :<\/code><\/strong> It works similarly to postgres described above, but pg_ctl <\/code>is more useful.<\/p>\n\n\n\n
# Runs in the background and redirects the log to the\npostgresql.log file.\n\npostgres@srv1:~$ pg_ctl start -l postgresql.log\n\n# -D option can be used here as well.\n\npg_ctl -D \/pg\/data\/13.6\/ -l postgresql.log 2>&1 &\n\n# Status, stop and restart options are also available.\n\npostgres@srv1:~$ pg_ctl status\/stop\/restart -l postgresql.log\n\n# Reload reads the configuration file and enables the settings\nthat do not require a restart.\n\npostgres@srv1:~$ pg_ctl reload -D \/pg\/data\/13.6\n\n# \u2018promote\u2019 option switches the hot standby server to primary,\nthat is, it opens it for writing and reading.\n\npostgres@srv1:~$ pg_ctl promote -D \/pg\/data\/13.6<\/pre>\n\n\n\n
\n\n\n\n
# With root privilege, systemctl can be started and stopped.\n\nsudo systemctl start\/stop\/restart postgresql@14-main.service\n\n# To check status\n\nsudo systemctl status postgresql@14-main.service\n\n# With enable option, it automatically starts and stops\npostgres on startup and shutdown.\n\nsudo systemctl enable postgresql@14-main.service<\/pre>\n\n\n\n
\n\n\n\n
systemctl :<\/strong><\/code>Startup and shutdown scripts can be integrated with the operating system\u2019s
systemd service management tool. The database can be automatically stopped and
started when the operating system is shut down or booted. Systemd services come
automatically when installed from in-build packages.<\/p>\n\n\n\n
pg_ctlcluster : <\/strong><\/code>Simplifies systemd integration. In multi-cluster environments, it calls the
cluster directory of the database to be processed and the correct pg_ctl.<\/code><\/p>\n\n\n\n
 Checking Instance<\/h2>\n\n\n\n
pgrep -u postgres -fa -- -D\n\n5932 \/pg\/home\/13.6\/bin\/postgres -D \/pg\/data\/13.6 --config-file=\/pg\/data\/13.6\/postgresql.conf\n\npgrep -fa -- -D |grep postgres\n\n5932 \/pg\/home\/13.6\/bin\/postgres -D \/pg\/data\/13.6 \u2013config file=\/pg\/data\/13.6\/postgresql.conf\n\n# Port information\n\nsed -n 4p $PGDATA\/postmaster.pid\n5434\n# or\nsed<\/pre>\n\n\n\n
\n\n\n\n
With pgrep and sed tools, it is possible to get information such as the process
number (PID) and TCP port of the config file where the instance is running.<\/p>\n\n\n\n
Stopping Postgresql Instance<\/h2>\n\n\n\n
postgres@srv1:~$ pg_ctl -D \/pg\/data\/13.6 stop -m s\n\nwaiting for server to shut down....................... done\n\npostgres@srv1:~$ pg_ctl -D \/pg\/data\/13.6 stop -m f\n\nwaiting for server to shut down.... done\nserver stopped\n\npostgres@srv1:~$ pg_ctl -D \/pg\/data\/13.6 stop -m i\n\nwaiting for server to shut down.... done\nserver stopped<\/pre>\n\n\n\n
\n\n\n\n
Smart Mode:<\/strong> (SIGTERM) New sessions (connections) are not allowed. It doesn\u2019t
terminate existing sessions, it will let it run. However, it stops the instance when all
sessions are terminated. In a production environment database, you may have to wait
long time (maybe months) for all sessions to expire.<\/p>\n\n\n\n
Fast Mode: <\/strong>(SIGINT) New sessions (connections) are not allowed. Terminates current
sessions. if it is committed, all sessions are terminated and if the user does not commit,
it rollbacks. Stops fast and consistent. No recovery is required at startup. It is the
default shutdown mode.<\/p>\n\n\n\n
Immediate Mode:<\/strong> Immediately terminates all server processes. It\u2019s the same as
unplugging the server\u2019s power.
The changed buffer area is closed inconsistently because the datafiles cannot be
written and the uncommitted changes cannot be rolled back.
Requires recovery from transaction (WAL \u2013 write-ahead-log) log files at startup.<\/p>\n","protected":false},"excerpt":{"rendered":"
Starting Postgresql Instance If installed from pre-built packages (yum\/apt install postgresql\u2026), services arecreated according to the operating system. Thus, it can be stopped and started withsystemctl commands and its startup can be automated (systemctl enablepostgres). Note: In the appendix chapters, where the installation and architecture from the prebuiltpackage were explained, and in the first chapter, …  Starting and Stopping Postgresql Instance<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[284],"tags":[],"class_list":["post-628","post","type-post","status-publish","format-standard","hentry","category-instance-network-connection-management"],"_links":{"self":[{"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/posts\/628","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/comments?post=628"}],"version-history":[{"count":0,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/posts\/628\/revisions"}],"wp:attachment":[{"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/media?parent=628"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/categories?post=628"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/tags?post=628"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}