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What Is PostgreSQL Logical Replication and When Should You Use It?

PostgreSQL's logical replication allows flexible and controlled data distribution between systems. In this post, we explain its use cases, benefits, and practical implementation examples.

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What Is Logical Replication in PostgreSQL?

Introduced in PostgreSQL 10, Logical Replication enables the replication of individual database objects—mainly tables—at the row level from one database (publisher) to one or more others (subscribers).

Unlike physical (binary) replication, logical replication is highly customizable, allowing selective replication of data and supporting heterogeneous replication setups between different PostgreSQL versions.

Why Use Logical Replication?

Logical replication is preferred over physical replication in scenarios where flexibility and control over data flow are critical:

  • 🔄 Real-time data sync between applications or across geographically distributed systems.
  • 🎯 Selective table replication, instead of cloning the entire database.
  • 🧪 Zero-downtime database migrations from one version to another.
  • ⚙️ Cross-version replication, useful when publisher and subscriber use different PostgreSQL versions.
  • 📤 Reporting or read-only replicas to reduce load on primary systems.

Common Use Cases

Logical replication can be useful in many industries and architectural designs:

  • 📊 Business Intelligence & Analytics: Real-time data feeds from production to a data warehouse.
  • 🚀 Staging or testing environments: Keeping test systems updated with fresh production data.
  • 🌍 Multi-region deployments: Improve read performance by placing data closer to users.
  • 🛡️ Disaster recovery setups with minimal lag and no downtime.

How Does It Work?

Logical replication involves setting up a publisher on the source and a subscriber on the target:

  1. Create a publication on the source:
CREATE PUBLICATION my_publication FOR TABLE customers, orders;
  1. Create a subscription on the target:
CREATE SUBSCRIPTION my_subscription
  CONNECTION 'host=source-db port=5432 user=replicator password=secret dbname=mydb'
  PUBLICATION my_publication;

3.Replication begins automatically, and changes to the specified tables (INSERT/UPDATE/DELETE) are streamed to the subscriber.

Monitoring Logical Replication with pghealth While powerful, logical replication can encounter issues such as:

1- Replication lag
2- Slot inactivity

pghealth helps ensure replication health and continuity with:

📈 Real-time monitoring of replication lag

⚠️ Alerts when a replication slot is delayed or disconnected

📊 Visibility into throughput and table-specific replication metrics

🔍 Discovery of all publications and subscriptions across environments

With these insights, you can detect problems before they impact your data flow or system integrity.

Final Thoughts PostgreSQL's Logical Replication is a robust and flexible tool for controlled data replication. Whether you're syncing data across regions, creating read-only replicas, or preparing for a major migration, logical replication enables scalable and real-time solutions.

For teams that rely on PostgreSQL at the core of their infrastructure, having visibility into replication health is critical.

pghealth helps you monitor, understand, and act on the health of your PostgreSQL infrastructure—including logical replication setups. Questions? Reach us at admin@pghealth.io