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How to Set Up Replication in Postgresql for High Availability?

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PostgreSQL Replication

Replication in PostgreSQL is a crucial technique to ensure high availability and data redundancy. By setting up replication, your PostgreSQL database can maintain a real-time copy on a standby server. This article will guide you through the process of configuring replication in PostgreSQL, providing a robust solution for your database management needs.

What is PostgreSQL Replication?

PostgreSQL replication involves copying data from one database server (the primary) to another (the standby or replica) to ensure data durability and availability. It can help in load balancing, failover scenarios, and in maintaining a distributed data architecture.

Prerequisites

Before setting up replication, ensure you meet the following prerequisites:

  1. Installed PostgreSQL: Make sure PostgreSQL is installed on both the primary and standby servers.
  2. Network Configuration: Configure your network to allow communication between servers.
  3. Superuser Access: You need superuser access on both database servers.

Step-by-Step Guide to Setting up PostgreSQL Replication

Step 1: Configure the Primary Server

  1. Edit the postgresql.conf file on the primary server, usually located in /etc/postgresql/<version>/main/:

    conf wal_level = replica max_wal_senders = 3 wal_keep_segments = 64

  2. Edit the pg_hba.conf file to allow replication connections from the standby server:

    plaintext host replication all <standby_ip_address>/32 md5

  3. Create a replication role:

    sql CREATE ROLE rep_user WITH REPLICATION LOGIN PASSWORD 'yourpassword';

Step 2: Prepare the Standby Server

  1. Take a base backup of your primary database using pg_basebackup:

    bash pg_basebackup -h <primary_ip_address> -U rep_user -D /var/lib/postgresql/<version>/main/ -Fp -Xs -P

  2. Edit the recovery.conf file in the data directory of the standby server:

    conf standby_mode = 'on' primary_conninfo = 'host=<primary_ip_address> port=5432 user=rep_user password=yourpassword' restore_command = 'cp /var/lib/postgresql/wal_archive/%f %p' trigger_file = '/tmp/postgresql.trigger.5432'

Step 3: Start the Standby Server

After the configuration, start the PostgreSQL service on the standby server:

sudo systemctl start postgresql

Verify the Replication Setup

  1. Check Replication Status: On the primary server, run:

    sql SELECT * FROM pg_stat_replication;

  2. Test the Setup: Write some test data into the primary server and confirm its presence on the standby server.

Additional Resources

Understanding how to connect your database and expand its functionality is crucial. For further details, check out these resources on PostgreSQL database connection, Flutter integration, and more about managing PostgreSQL databases.

By following this guide, you have successfully set up replication in PostgreSQL, providing your infrastructure with high availability and ensuring your data is reliably mirrored across servers. This setup is critical in scenarios requiring minimal downtime and efficient disaster recovery solutions.