Introduction

PostgreSQL has gained so much popularity in recent years due to its robust features. These features include the storage of advanced data structures (e.g., JSON, arrays), scalability for high-traffic environments, and a rich set of functionalities specifically designed for data handling. Additionally, PostgreSQL offers many other benefits.

In this short article, I will briefly discuss a simple way to create multiple PostgreSQL instances on a single machine. This is a very common scenario, depending on your usage. In my case, I wanted to test two services that will coexist in different environments.

Requirements

Installed PostgreSQL (Any version)
Ubuntu (any version)

We’ll assume you already have a running PostgreSQL server on port 5432.

Steps of creating a second instance

Open the bash and run the following command

Use name of your choice for “main1” folder and the port number.Use any port number but not 5432 as By default, PostgreSQL is configured to run on port 5432. If you want to run a second instance, you’ll need to configure it to use a different port.
This command creates another PostgreSQL cluster named main1 and
starts it on port 5433.

2.
Running this command will result to this:

3.
Modify Postgres configuration file to allow change of password:
When you try to access the new service, you will be denied entry. To ease the process of changing your password, navigate to this folder and open the pg_hba.conf file with your favorite text editor. Please note that the version of PostgreSQL may differ.

4.
Scroll down to this section:

and make the following changes:

NB:

Remember to revert these changes back to the original configuration after resetting your passwords. These changes may pose a threat to your database security.
5.
Accessing the Instances:

6.
Change the password:

restart the server.

And update the Postgres configuration file back to the original settings.

to check the number of postgres instance running, use the following command:

for my case you can see I have 3 instances running

Useful commands to manage your instances

for this example, we shall assume the service is in folder main2

To start service

To stop service

To restart service

Thank you!