PostgreSQL, also goes by the name "Postgres", is an open-source, object-oriented relational Database Management System. It is used by many applications to store data. This database supports many cutting-edge features like reliable transactions and concurrency.
MacOS server uses PostgreSQL as its default database. It is also available for Linux, Windows, FreeBSD, and OpenBSD.
Here at LinuxAPT, we shall look into how you can easily install PostgreSQL on Ubuntu 20.04 with the help of a few simple commands.
You can also see how to install PostgreSQL on Linux Mint.
1. Perform System Update
To begin, ensure that the packages of the system is up to date with the below command:
$ sudo apt update
2. Install PostgreSQL
Now, we will install the PostgreSQL package along with the contrib package which is needed to add some additional utilities and functionality. Use the following command to do that:
$ sudo apt install postgresql postgresql-contrib
3. Configure PostgreSQL Roles and Databases
Now that we have successfully installed PostgreSQL, let's get ourselves a little familiar with the PostgreSQL roles and databases.
Roles are meant to handle authentication and authorization of the PostgreSQL databases.
When we install PostgreSQL, by default a Postgres user is created. To switch to this user, run this command:
$ sudo -i -u postgres
Next, we will access the Postgres prompt. This prompt will let you communicate with the database management system.
To do that, run the following command:
You can exit the prompt using the below command:
You can go back in the postgres Linux command prompt. To go back to your regular system, run the exit command:
One more way to enter the postgres prompt is by running the psql command directly with sudo:
$ sudo -u postgres psql
To quit the interactive Postgres session, you can run the command:
4. Create New Role
Once you are logged in from your postgres account, you can make a new role by running the following command:
You can also switch directly from your normal account using sudo:
$ sudo -u postgres createuser --interactive
You will be prompted to enter the name of the role. It will also ask you to confirm if the new role can be a superuser or not.
5. Create Database for PostgreSQL
When you create a user in postgreSQL, its authentication system thinks that the role that you have used to log in, will have a database associated with it with the same name that it can access.
Didn't understand what I just said?
Let me make it a little clear for you. This means, that the user "John" that we previously created, will try to connect to a database with the same name as the role.
You can create a database having the same name as the role, using the following command:
An alternative method to make a database is by using sudo directly from your normal account by running this:
$ sudo -u postgres createdb John
6. Open Postgres Prompt with a new role
To log in with ident-based authentication, you need to have a Linux user with the same name as your Postgres role and database. If you don't have one, don't worry, you can create it using the adduser command. You will have to do this with your non-root account using sudo privileges:
$ sudo adduser John
After that, you can connect to the database by running these two commands:
$ sudo -i -u John
Or instead, you can use a simple one-line command:
$ sudo -u John psql
To interact with a different database, run the following command by mentioning the database:
psql -d postgres
To check the status of your current connection, run the conninfo command. It will provide you information of your database connection:
This article covers how to install PostgreSQL on your Ubuntu 20.04 LTS machine. In fact, PostgreSQL, or Postgres, is a relational database management system that provides an implementation of the SQL querying language. It's standards-compliant and has many advanced features like reliable transactions and concurrency without read locks.
Service commands for PostgreSQL
The PostgreSQL database server runs as a service under the name "postgresql". You can manage the service by running the commands below.
1. Stop PostgreSQL server:
$ sudo systemctl stop postgresql
2. Start PostgreSQL server:
$ sudo systemctl start postgresql
3. Restart PostgreSQL(e.g. after changing configuration settings) server:
$ sudo systemctl restart postgresql
4. Reload PostgreSQL server:
$ sudo systemctl reload postgresql
5. Check PostgreSQL status:
$ sudo systemctl status postgresql