Step-by-Step Process to Uninstall PostgreSQL on Ubuntu

Preparing for Uninstallation

Before uninstalling PostgreSQL on Ubuntu, it is important to prepare for the process to ensure a smooth removal. Here are the steps to follow:

1. Make sure you have administrative privileges on your Ubuntu system.
2. Backup any important data or databases stored in PostgreSQL. This is crucial to prevent data loss during the uninstallation process.
3. Ensure that you have an alternative database management system or a backup plan in place if you need to access databases after uninstalling PostgreSQL.

Related Article: How to Check and Change Postgresql's Default Port

Checking PostgreSQL Installation

Before proceeding with the uninstallation process, it is essential to verify that PostgreSQL is installed on your Ubuntu system. Here’s how you can check:

1. Open a terminal window on your Ubuntu system.
2. Type the following command to check if PostgreSQL is installed:

dpkg -l | grep postgresql

3. If PostgreSQL is installed, you will see a list of packages related to PostgreSQL. If you don’t see any output, it means PostgreSQL is not installed on your system.

Backing Up PostgreSQL Data

Before uninstalling PostgreSQL, it is crucial to back up any data or databases that you want to retain. Here’s how you can back up PostgreSQL data:

1. Open a terminal window on your Ubuntu system.
2. Enter the following command to create a backup of the PostgreSQL data directory:

sudo cp -R /var/lib/postgresql /var/lib/postgresql_backup

3. This command will create a backup of the PostgreSQL data directory and store it in the /var/lib/postgresql_backup directory.

Disabling PostgreSQL Services

Before uninstalling PostgreSQL, it is necessary to disable the PostgreSQL services to ensure a clean removal. Follow these steps:

1. Open a terminal window on your Ubuntu system.
2. Disable the PostgreSQL service by running the following command:

sudo systemctl disable postgresql

3. This command will disable the PostgreSQL service from starting automatically on system boot.

Related Article: How to Create a Database from the Command Line Using Psql

Removing PostgreSQL Packages

To uninstall PostgreSQL on Ubuntu, you need to remove the PostgreSQL packages installed on your system. Here’s how you can do it:

1. Open a terminal window on your Ubuntu system.
2. Run the following command to uninstall the PostgreSQL packages:

sudo apt-get purge postgresql-

Replace with the specific version of PostgreSQL installed on your system. For example, if you have PostgreSQL 12 installed, the command would be sudo apt-get purge postgresql-12.

3. Confirm the uninstallation by typing Y when prompted.

Removing PostgreSQL Dependencies

After removing the PostgreSQL packages, it is important to remove any remaining dependencies. Here’s how you can do it:

1. Open a terminal window on your Ubuntu system.
2. Run the following command to remove the PostgreSQL dependencies:

sudo apt-get autoremove

3. This command will remove any unused dependencies, including those related to PostgreSQL.

Removing PostgreSQL Configuration Files

To completely uninstall PostgreSQL, you need to remove the configuration files associated with it. Follow these steps:

1. Open a terminal window on your Ubuntu system.
2. Remove the PostgreSQL configuration files by running the following command:

sudo rm -rf /etc/postgresql

3. This command will delete the PostgreSQL configuration files from the /etc/postgresql directory.

Related Article: How to Restore a Postgresql Backup File Using the Command Line

Removing PostgreSQL Data Directory

To ensure a clean uninstallation, it is important to remove the PostgreSQL data directory. Here’s how you can do it:

1. Open a terminal window on your Ubuntu system.
2. Remove the PostgreSQL data directory by running the following command:

sudo rm -rf /var/lib/postgresql

3. This command will delete the PostgreSQL data directory and all its contents.

Cleaning Up Remaining Files and Directories

After uninstalling PostgreSQL, there might be some remaining files and directories that need to be cleaned up. Here’s how you can do it:

1. Open a terminal window on your Ubuntu system.
2. Run the following command to remove the remaining PostgreSQL files and directories:

sudo find / -iname "*postgres*" -exec rm -rf {} \;

3. This command will search for any files or directories containing the word “postgres” and delete them.

Verifying Successful Uninstallation

To ensure that PostgreSQL has been successfully uninstalled from your Ubuntu system, follow these steps:

1. Open a terminal window on your Ubuntu system.
2. Type the following command to check if PostgreSQL is still installed:

dpkg -l | grep postgresql

3. If there is no output, it means that PostgreSQL has been successfully uninstalled from your system.

Related Article: Tutorial: Managing PostgreSQL Databases with Vacuumdb

Reinstalling PostgreSQL (Optional)

If you decide to reinstall PostgreSQL after uninstalling it, here’s how you can do it:

1. Open a terminal window on your Ubuntu system.
2. Run the following command to install PostgreSQL:

sudo apt-get install postgresql

3. This command will install the latest version of PostgreSQL available in the Ubuntu repositories.

Precautions Before Uninstalling PostgreSQL

Before uninstalling PostgreSQL, it is important to keep the following precautions in mind:

1. Backup any important data or databases stored in PostgreSQL to prevent data loss.
2. Make sure you have an alternative database management system or a backup plan in place if you need to access databases after uninstalling PostgreSQL.
3. Double-check that you are uninstalling the correct version of PostgreSQL to avoid unintended consequences.

Troubleshooting Common Issues

If you encounter any issues during the uninstallation process, here are some common problems and their solutions:

1. Problem: Unable to uninstall PostgreSQL due to dependency issues.
Solution: Use the apt-get command with the --fix-broken option to fix any dependency issues before uninstalling PostgreSQL.

2. Problem: PostgreSQL service is still running after uninstallation.
Solution: Manually stop the PostgreSQL service using the systemctl command and then proceed with the uninstallation.

Related Article: How to Create a PostgreSQL Read Only User

Uninstalling PostgreSQL Without Affecting Other Databases

If you have multiple databases installed on your Ubuntu system and want to uninstall PostgreSQL without affecting other databases, follow these steps:

1. Open a terminal window on your Ubuntu system.
2. Run the following command to uninstall PostgreSQL without removing other databases:

sudo apt-get remove --purge postgresql-

Replace with the specific version of PostgreSQL you want to uninstall.

Uninstalling PostgreSQL Using Package Manager

Another method to uninstall PostgreSQL on Ubuntu is by using the package manager. Here’s how you can do it:

1. Open a terminal window on your Ubuntu system.
2. Run the following command to uninstall PostgreSQL using the package manager:

sudo apt-get remove --purge postgresql

3. Confirm the uninstallation by typing Y when prompted.

Alternative Methods of Uninstalling PostgreSQL

Apart from the methods mentioned above, there are alternative ways to uninstall PostgreSQL on Ubuntu:

1. Using the Synaptic Package Manager: Open the Synaptic Package Manager, search for “postgresql,” select the packages you want to uninstall, and click on the “Mark for Removal” option. Apply the changes to uninstall PostgreSQL.

2. Manually removing packages: If you know which specific packages are installed, you can manually remove them using the dpkg command. For example:

sudo dpkg --remove postgresql-

Replace with the specific version of PostgreSQL you want to uninstall.

Related Article: How to Check & Change the DB Directory in PostgreSQL

Removing PostgreSQL Database

If you want to remove a specific PostgreSQL database, you can do it using the dropdb command. Here’s an example:

1. Open a terminal window on your Ubuntu system.
2. Run the following command to remove a PostgreSQL database:

sudo -u postgres dropdb 

Replace with the name of the database you want to remove.

Command to Uninstall PostgreSQL

To summarize, here is the command to uninstall PostgreSQL on Ubuntu:

sudo apt-get remove --purge postgresql-

Replace with the specific version of PostgreSQL you want to uninstall.

Recommended Method to Uninstall PostgreSQL

The recommended method to uninstall PostgreSQL on Ubuntu is as follows:

1. Backup any important data or databases stored in PostgreSQL.
2. Disable the PostgreSQL services to prevent them from starting automatically.
3. Remove the PostgreSQL packages and dependencies using the package manager.
4. Delete the PostgreSQL configuration files and data directory.
5. Clean up any remaining files and directories related to PostgreSQL.
6. Verify the successful uninstallation by checking for any remaining PostgreSQL packages.
7. Optionally, reinstall PostgreSQL if needed.

Related Article: How to Disable IPv6 in PostgreSQL Databases

Reinstalling PostgreSQL After Uninstallation

If you decide to reinstall PostgreSQL after uninstalling it, you can follow the steps mentioned in the “Reinstalling PostgreSQL” section above.

Additional Resources

– How to Install PostgreSQL on Ubuntu
– Configuring PostgreSQL on Ubuntu
– Popular SQL Databases Besides PostgreSQL