mcp-database-server/docs/postgresql-setup.md

PostgreSQL Setup for MCP Database Server

This document describes how to set up and use the PostgreSQL adapter with the MCP Database Server.

Prerequisites

1. You need to have PostgreSQL installed and running on your system or on a remote server.
2. Ensure the pg package is installed:

npm install pg
npm install @types/pg --save-dev

Running the Server with PostgreSQL

To connect to a PostgreSQL database, use the following command-line arguments:

# Basic connection
node dist/src/index.js --postgresql --host localhost --database yourdb --user postgres --password yourpassword

# With custom port (default is 5432)
node dist/src/index.js --postgresql --host localhost --database yourdb --user postgres --password yourpassword --port 5433

# With SSL enabled
node dist/src/index.js --postgresql --host localhost --database yourdb --user postgres --password yourpassword --ssl true

Command Line Arguments

• --postgresql or --postgres: Specifies that you want to connect to a PostgreSQL database.
• --host: The hostname or IP address of the PostgreSQL server (required).
• --database: The name of the database to connect to (required).
• --user: The PostgreSQL user to authenticate as.
• --password: The password for the PostgreSQL user.
• --port: The port the PostgreSQL server is listening on (default: 5432).
• --ssl: Whether to use SSL for the connection (true/false).

Usage from MCP Client

The MCP client can interact with a PostgreSQL database using the same tools that are available for SQLite and SQL Server. The server automatically translates the generic SQL queries to PostgreSQL-specific formats.

Supported Features

• Full SQL query support for SELECT, INSERT, UPDATE, and DELETE operations.
• Table management (CREATE TABLE, ALTER TABLE, DROP TABLE).
• Schema introspection.
• Connection pooling for efficient database access.
• SSL support for secure connections.

Examples

Create a Table

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    username VARCHAR(50) NOT NULL,
    email VARCHAR(100) UNIQUE NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Insert Data

INSERT INTO users (username, email) VALUES ('johndoe', 'john@example.com');

Query Data

SELECT * FROM users WHERE username = 'johndoe';

Limitations

• For the run method with INSERT statements, the adapter attempts to retrieve the last inserted ID by adding a RETURNING clause. This assumes your tables have an 'id' column.
• Complex stored procedures or PostgreSQL-specific features might require custom implementation.

Troubleshooting

Connection Issues

If you're having trouble connecting to your PostgreSQL database:

1. Verify that PostgreSQL is running: pg_isready -h localhost -p 5432
2. Check that your credentials are correct.
3. Ensure that the database exists and the user has appropriate permissions.
4. Check firewall settings if connecting to a remote database.

Query Errors

If your queries are failing:

1. Check the syntax against PostgreSQL's SQL dialect.
2. Verify table and column names.
3. Check that the user has proper permissions for the operations.

Performance Considerations

For optimal performance:

1. Use parameterized queries to prevent SQL injection and improve query caching.
2. Consider indexing frequently queried columns.
3. For large result sets, use LIMIT and OFFSET for pagination.