Install Pgpool-II for PostgreSQL on CentOS: How-To Guide

Pgpool-II is a robust middleware solution specifically created to optimize the performance, scalability, and high availability of PostgreSQL databases. With its advanced features like connection pooling, load balancing, and replication, Pgpool-II becomes an invaluable asset for effectively managing PostgreSQL deployments. In this comprehensive installation guide, we will guide you through a detailed step-by-step process to seamlessly install and configure Pgpool-II on CentOS, enabling you to leverage its powerful capabilities to enhance your PostgreSQL environment.

Step 1: Installing Pgpool-II on CentOS

To begin, follow these steps to install Pgpool-II on CentOS:

1. Update the package list:

   sudo yum update

2. Install the required dependencies:

   sudo yum install -y epel-release
   sudo yum install -y pgpool-II-extensions

Step 2: Configuring Pgpool-II

After installing Pgpool-II, proceed with the configuration process:

1. Open the Pgpool-II configuration file in a text editor:

   sudo vi /etc/pgpool-II/pgpool.conf

2. Configure the Pgpool-II parameters based on your environment and requirements. Some key parameters to consider are:

• listen_addresses: Set the IP address or hostname on which Pgpool-II will listen for incoming connections.
• backend_hostname: Specify the hostnames or IP addresses of your PostgreSQL servers.
• backend_port: Define the port numbers on which the PostgreSQL servers are listening.
• backend_weight: Assign weights to the PostgreSQL servers to control load distribution. Make the necessary changes to these parameters and save the file.

Step 3: Starting Pgpool-II

To start the Pgpool-II service, execute the following command:

sudo systemctl start pgpool-II

To enable automatic start at system boot, run the following command:

sudo systemctl enable pgpool-II

Additional Configuration Options

Pgpool-II provides several additional configuration options that can be adjusted based on your specific needs. Some notable options include:

• num_init_children: Sets the number of child processes that Pgpool-II will create to handle incoming connections.
• load_balance_mode: Determines the load balancing behavior, such as using a round-robin algorithm or weighted load balancing.
• replication_mode: Specifies the replication mode, including streaming replication or logical replication.
• health_check_period: Defines the interval for health checks to monitor the status of PostgreSQL servers.

Refer to the Pgpool-II documentation for a comprehensive list of configuration parameters and their explanations.

Installing Pgpool Admin on CentOS: Step-by-Step Guide

Pgpool Admin is a web-based administration tool for managing Pgpool-II deployments. It provides a user-friendly interface to configure, monitor, and control Pgpool-II instances. Follow these step-by-step instructions to install Pgpool Admin on CentOS:

1. Install the required dependencies:

   sudo yum install -y httpd php php-pgsql

2. Start and enable the Apache web server:

   sudo systemctl start httpd
   sudo systemctl enable httpd

3. Download the Pgpool Admin package from the official website (e.g., http://www.pgpool.net/mediawiki/index.php/Downloads):

   wget http://www.pgpool.net/download.php?f=pgpoolAdmin-4.2.2.tar.gz -O pgpoolAdmin.tar.gz

4. Extract the downloaded package:

   tar xvfz pgpoolAdmin.tar.gz

5. Move the extracted directory to the Apache web root directory:

   sudo mv pgpoolAdmin-4.2.2 /var/www/html/pgpoolAdmin

6. Grant necessary permissions to the Apache web server:

   sudo chown -R apache:apache /var/www/html/pgpoolAdmin

7. Create a new Apache configuration file for Pgpool Admin:

   sudo nano /etc/httpd/conf.d/pgpoolAdmin.conf

8. Add the following content to the configuration file:

   <VirtualHost *:80>
       ServerAdmin admin@example.com
       DocumentRoot /var/www/html/pgpoolAdmin
       ServerName your_domain_or_IP
       ErrorLog /var/log/httpd/pgpoolAdmin-error.log
       CustomLog /var/log/httpd/pgpoolAdmin-access.log combined
       <Directory /var/www/html/pgpoolAdmin>
           Options FollowSymLinks
           AllowOverride All
           Require all granted
       </Directory>
   </VirtualHost>

Replace your_domain_or_IP with your actual domain name or IP address.

9. Save the configuration file and exit the editor.
10. Restart the Apache web server to apply the changes: sudo systemctl restart httpd
11. Access Pgpool Admin through your web browser by entering http://your_domain_or_IP/pgpoolAdmin.

By following these step-by-step instructions, you have successfully installed Pgpool Admin on CentOS. Pgpool Admin provides a web-based interface for easy configuration and monitoring of Pgpool-II instances. You can now utilize the user-friendly interface to manage and control your Pgpool-II deployments efficiently.