PostgreSQL MCP Server

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A Model Context Protocol (MCP) server that provides tools for interacting with a PostgreSQL database. This server enables AI assistants to execute SQL queries, create tables, and list database tables through the MCP protocol.

Features

The server provides the following tools:

• read_query: Execute SELECT queries on the PostgreSQL database
• write_query: Execute INSERT, UPDATE, or DELETE queries on the PostgreSQL database
• create_table: Create a new table in the PostgreSQL database
• list_tables: List all user tables in the database (with optional schema filtering)
• explain_query：EXPLAIN a query on the PostgreSQL database

Installation

Prerequisites

• Go 1.23 or later
• PostgreSQL database server

Steps

1. Clone the repository:

   git clone https://github.com/sql-mcp-server.git
   cd sql-mcp-server

2. Install dependencies:

   go mod download

3. Build the server:

   go build -o sql-mcp-server

Configuration

The server requires database connection details through environment variables. Create a .env file in the project root with the following variables:

DB_HOST=localhost      # PostgreSQL server host
DB_PORT=5432           # PostgreSQL server port
DB_NAME=postgres       # Database name
DB_USER=your_username  # Database user
DB_PASSWORD=your_pass  # Database password
DB_SSLMODE=disable     # SSL mode (disable, require, verify-ca, verify-full)

Usage

Running the Server

./sql-mcp-server

MCP Configuration

To use this server with an AI assistant that supports MCP, add the following to your MCP configuration:

{
  "mcpServers": {
    "pgsql-mcp-server": {
      "command": "/path/to/sql-mcp-server",
      "args": [],
      "env": {
        "DB_HOST": "localhost",
        "DB_PORT": "5432",
        "DB_NAME": "postgres",
        "DB_USER": "your_username",
        "DB_PASSWORD": "your_password",
        "DB_SSLMODE": "disable"
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

Tool Examples

List Tables

List all user tables in the database:

{
  "server_name": "pgsql-mcp-server",
  "tool_name": "list_tables",
  "arguments": {}
}

List tables in a specific schema:

{
  "server_name": "pgsql-mcp-server",
  "tool_name": "list_tables",
  "arguments": {
    "schema": "public"
  }
}

Create Table

Create a new table:

{
  "server_name": "pgsql-mcp-server",
  "tool_name": "create_table",
  "arguments": {
    "schema": "CREATE TABLE users (id SERIAL PRIMARY KEY, name VARCHAR(100), email VARCHAR(100) UNIQUE, created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP)"
  }
}

Read Query

Execute a SELECT query:

{
  "server_name": "pgsql-mcp-server",
  "tool_name": "read_query",
  "arguments": {
    "query": "SELECT * FROM users LIMIT 10"
  }
}

Write Query

Execute an INSERT query:

{
  "server_name": "pgsql-mcp-server",
  "tool_name": "write_query",
  "arguments": {
    "query": "INSERT INTO users (name, email) VALUES ('John Doe', '[email protected]')"
  }
}

Execute an UPDATE query:

{
  "server_name": "pgsql-mcp-server",
  "tool_name": "write_query",
  "arguments": {
    "query": "UPDATE users SET name = 'Jane Doe' WHERE id = 1"
  }
}

Execute a DELETE query:

{
  "server_name": "pgsql-mcp-server",
  "tool_name": "write_query",
  "arguments": {
    "query": "DELETE FROM users WHERE id = 1"
  }
}

Security Considerations

• The server validates query types to ensure that only appropriate operations are performed with each tool.
• Input sanitization is performed for schema names to prevent SQL injection.
• Consider using a dedicated database user with limited permissions for this server.
• In production environments, enable SSL by setting DB_SSLMODE to require or higher.

Dependencies

• github.com/joho/godotenv - For loading environment variables from .env file
• github.com/lib/pq - PostgreSQL driver for Go
• github.com/mark3labs/mcp-go - Go SDK for Model Context Protocol

License

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Contributing

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