PostgreSQL Replication Status Monitor

Overview

Build a Node.js application that connects to a PostgreSQL server in replication mode to monitor replication status and slot information. The application should establish a special connection that allows querying replication-specific system views.

Requirements

Connection Configuration

Create a connection that enables replication mode. The connection should:

• Connect to a PostgreSQL server
• Enable special replication protocol capabilities
• Handle connection errors appropriately

Replication Information Query

Implement functionality to query and display replication information:

1. Query the pg_replication_slots system view to retrieve active replication slots
2. Extract and display the following information for each slot:
   • Slot name
   • Slot type
   • Database name
   • Active status
3. Handle cases where no replication slots exist

Output Format

Display the retrieved information in a clear, structured format. For each replication slot, show all relevant fields.

Error Handling

• Handle connection failures gracefully
• Handle cases where replication features are not available
• Display appropriate error messages

Dependencies { .dependencies }

pg { .dependency }

PostgreSQL client for Node.js providing connection management and query execution.

Test Cases

Test 1: Replication Mode Connection @test

File: replication.test.js

Test Description: Verify that the connection can be established with replication mode enabled.

Expected Behavior:

• Connection should be created with replication mode configuration
• Connection should successfully connect to the PostgreSQL server without errors
• Connection should be able to query replication-specific views

Test 2: Query Replication Slots @test

File: replication.test.js

Test Description: Verify that the application can query and retrieve replication slot information.

Expected Behavior:

• Should successfully execute query against pg_replication_slots
• Should return results containing slot information (or empty array if no slots)
• Should handle the query result correctly

Test 3: Handle Empty Replication Slots @test

File: replication.test.js

Test Description: Verify proper handling when no replication slots are configured.

Expected Behavior:

• Query should succeed even with no replication slots
• Should return empty result set
• Should not throw errors for empty results

Implementation Notes

• Use appropriate connection configuration options to enable replication features
• Ensure proper resource cleanup (close connections when done)
• The application should work with PostgreSQL 10 or later
• Consider that replication mode connections have different capabilities than normal connections