How To Restart Postgresql?

Postgresql or postgres can be restart in different ways in different platforms and operating systems. To restart PostgreSQL, you can use the appropriate command based on your operating system. Here are the common commands for different systems:

On Linux (systemd)

Postgresql is mostly used with Linux or Unix operating systems and most modern Linux distributions use systemd to manage services. We can use the systemctl restart command in order to restart postgresql service. The service is named as postgresql . Also you need to have root privileges which can be obtained with the sudo command. Alternatively you can login with root user in order to run without sudo command.

sudo systemctl restart postgresql

On Linux (older systems with init.d)

The init.d is another oppular service management tool which can be uesd to restart postgresql service. The service command is used to restart postgresql service like below. For systems using the init.d script:

sudo service postgresql restart

If you’re encountering errors while trying to restart PostgreSQL, here are some steps you can follow to diagnose and fix the issue:

PostgreSQL Restart Errors

During the PostgreSQL restart process you may face some errors which prevents the restart. You can do different things to troubleshoot the postgresql restart errors.

1. Check the Status of PostgreSQL

First, check the status to see if there are any obvious issues. The systemctl status command can be used to check and list errors related with the restart:

sudo systemctl status postgresql

or

service postgresql status

2. Look at the Logs

PostgreSQL logs can provide detailed information about what’s going wrong. The logs provides detailed information about the restart errors. The location of the logs may vary, but common places include:

• /var/log/postgresql/
• /var/lib/pgsql/data/pg_log/
• /usr/local/var/postgres/server.log

The log files are stored as clear text with the *.log file extension. You can view the logs using cat, less, or tail commands:

sudo tail -n 50 /var/log/postgresql/postgresql.log

3. Common Issues and Fixes

Port Conflict

The PostgreSQL use TCP port number 5432 to accept local and remote connections. If this port is used allready used this may result with restart error.Another service might be using the port PostgreSQL is trying to use. The default port is 5432. Check if the port is already in use:

sudo lsof -i :5432

If the port is in use, either stop the conflicting service or change the PostgreSQL port in the postgresql.conf file (usually found in /etc/postgresql/XX/main/ or /var/lib/pgsql/data/).

Alternatively you can stop the service or application using TCP port 5432 and try to restart PostgreSQL service again.

File Permission Issues

PostgreSQL generally use files and executables located /var/lib/postgresql and need permissions to read and write into this path. Ensure that the PostgreSQL data directory has the correct permissions:

sudo chown -R postgres:postgres /var/lib/postgresql/

or

sudo chown -R postgres:postgres /usr/local/var/postgres

Configuration Errors

Sometimes, configuration errors can prevent PostgreSQL from starting. Check the postgresql.conf and pg_hba.conf files for any syntax errors or misconfigurations.

sudo nano /etc/postgresql/XX/main/postgresql.conf
sudo nano /etc/postgresql/XX/main/pg_hba.conf

Look for typos or incorrect settings and correct them.

Disk Space Issues

Ensure you have enough disk space. Check available space with:

df -h

If you still encounter issues, providing the exact error messages or logs will help in diagnosing the problem further.

On MacOS (using Homebrew)

You can restart the Postgresql service in MacOS operating system with the brew command like below. If you installed PostgreSQL using Homebrew:

brew services restart postgresql

On Windows

You can use the net stop and net start commands in order to restart Postgresql in Windows operating system.

1. Open the Services application (you can find it by searching “Services” in the Start menu).
2. Find the PostgreSQL service in the list (it might be listed as postgresql-x64-XX where XX is the version number).
3. Right-click on the PostgreSQL service and select Restart.

Alternatively, you can use the command line:

net stop postgresql-x64-XX
net start postgresql-x64-XX

Make sure to replace XX with the appropriate version number of PostgreSQL installed on your system.