PostgreSQL is an object-relational database system that has the features of traditional commercial database systems with enhancements to be found in next-generation DBMS systems.
To install PostgreSQL, run the following command in the command prompt:
sudo apt install postgresql
Once the installation is complete, you should configure the PostgreSQL server based on your needs, although the default configuration is viable.
PostgreSQL supports multiple client authentication methods. IDENT authentication method is used for postgres and local users, unless otherwise configured. Please refer to the PostgreSQL Administrator's Guide if you would like to configure alternatives like Kerberos.
The following discussion assumes that you wish to enable TCP/IP connections and use the MD5 method for client authentication. PostgreSQLconfiguration files are stored in the /etc/postgresql/<version>/main directory. For example, if you install PostgreSQL 9.5, the configuration files are stored in the /etc/postgresql/9.5/main directory.
To configure ident authentication, add entries to the /etc/postgresql/9.5/main/pg_ident.conf file. There are detailed comments in the file to guide you.
To enable other computers to connect to your PostgreSQL server, edit the file /etc/postgresql/9.5/main/postgresql.conf
Locate the line #listen_addresses = 'localhost' and change it to:
listen_addresses = '*'
To allow both IPv4 and IPv6 connections replace 'localhost' with '::'
You may also edit all other parameters, if you know what you are doing! For details, refer to the configuration file or to the PostgreSQL documentation.
Now that we can connect to our PostgreSQL server, the next step is to set a password for the postgres user. Run the following command at a terminal prompt to connect to the default PostgreSQL template database:
sudo -u postgres psql template1
The above command connects to PostgreSQL database template1 as user postgres. Once you connect to the PostgreSQL server, you will be at a SQL prompt. You can run the following SQL command at the psql prompt to configure the password for the user postgres.
ALTER USER postgres with encrypted password 'your_password';
After configuring the password, edit the file /etc/postgresql/9.5/main/pg_hba.conf to use MD5 authentication with the postgres user:
local all postgres md5
Finally, you should restart the PostgreSQL service to initialize the new configuration. From a terminal prompt enter the following to restart PostgreSQL:
sudo systemctl restart postgresql.service
You can test server connections from other machines by using the PostgreSQL client.
sudo apt install postgresql-client psql -h postgres.example.com -U postgres -W
Replace the domain name with your actual server domain name.
PostgreSQL databases should be backed up regularly. Refer to the PostgreSQL Administrator's Guide for different approaches.
As mentioned above the PostgreSQL Administrator's Guide is an excellent resource. The guide is also available in the postgresql-doc-9.5 package. Execute the following in a terminal to install the package:
sudo apt install postgresql-doc-9.5
To view the guide enter file:///usr/share/doc/postgresql-doc-9.5/html/index.html into the address bar of your browser.
For general SQL information see Using SQL Special Edition by Rafe Colburn.
Also, see the PostgreSQL Ubuntu Wiki page for more information.