Secure PostgreSQL Management via MCP Server Workflow

This n8n workflow demonstrates a secure and structured approach to managing a PostgreSQL database through a custom MCP (Model Context Protocol) server. Designed for database administrators and developers, it allows safe execution of CRUD (Create, Read, Update, Delete) operations by leveraging a combination of trigger-based workflows and PostgreSQL nodes. The workflow begins with an MCP Server trigger node that listens for incoming requests from an MCP client. When triggered, the process offers three main operations: reading table data, creating new records, or updating existing records — all strictly routed through defined workflows to ensure security and control.

Key nodes include the ‘PostgreSQL MCP Server’ trigger, which initiates the process via webhooks, and various PostgreSQL nodes for execution of SQL commands. The data flow is controlled by a switch node that routes the request based on the specified operation type. For reading data, the workflow uses ‘ReadTableRecord’ and ‘ReadTableRows’ nodes, which execute parameterized SELECT queries. For inserting and updating data, respective nodes (‘CreateTableRecord’ and ‘UpdateTableRecord’) construct and execute INSERT and UPDATE SQL statements, safeguarding against SQL injection by not allowing raw SQL input.

The workflow facilitates dynamic JSON inputs where the operation type, table name, and data are received securely, making it versatile for managing multiple tables or operations. It displays best security practices by encouraging authentication, restricting raw SQL execution, and leveraging query parameters.

It’s especially useful in scenarios where multiple clients or systems need to interact with a PostgreSQL database securely, such as HR systems, inventory management, or support ticketing platforms, without exposing raw query capabilities or risking data breaches.