Multi Database MCP Server

Overview

The DB MCP Server provides a standardized way for AI models to interact with multiple databases simultaneously. Built on the FreePeak/cortex framework, it enables AI assistants to execute SQL queries, manage transactions, explore schemas, and analyze performance across different database systems through a unified interface.

Core Concepts

Multi-Database Support

Unlike traditional database connectors, DB MCP Server can connect to and interact with multiple databases concurrently:

{
  "connections": [
    {
      "id": "mysql1",
      "type": "mysql",
      "host": "localhost",
      "port": 3306,
      "name": "db1",
      "user": "user1",
      "password": "password1"
    },
    {
      "id": "postgres1",
      "type": "postgres",
      "host": "localhost",
      "port": 5432,
      "name": "db2",
      "user": "user2",
      "password": "password2"
    },
    {
      "id": "oracle1",
      "type": "oracle",
      "host": "localhost",
      "port": 1521,
      "service_name": "XEPDB1",
      "user": "user3",
      "password": "password3"
    }
  ]
}

Dynamic Tool Generation

For each connected database, the server automatically generates specialized tools:

// For a database with ID "mysql1", these tools are generated:
query_mysql1       // Execute SQL queries
execute_mysql1     // Run data modification statements
transaction_mysql1 // Manage transactions
schema_mysql1      // Explore database schema
performance_mysql1 // Analyze query performance

Clean Architecture

The server follows Clean Architecture principles with these layers:

1. Domain Layer: Core business entities and interfaces
2. Repository Layer: Data access implementations
3. Use Case Layer: Application business logic
4. Delivery Layer: External interfaces (MCP tools)

Features

• Simultaneous Multi-Database Support: Connect to multiple MySQL, PostgreSQL, SQLite, and Oracle databases concurrently
• Lazy Loading Mode: Defer connection establishment until first use - perfect for setups with 10+ databases (enable with --lazy-loading flag)
• Database-Specific Tool Generation: Auto-creates specialized tools for each connected database
• Clean Architecture: Modular design with clear separation of concerns
• OpenAI Agents SDK Compatibility: Full compatibility for seamless AI assistant integration
• Dynamic Database Tools: Execute queries, run statements, manage transactions, explore schemas, analyze performance
• Unified Interface: Consistent interaction patterns across different database types
• Connection Management: Simple configuration for multiple database connections
• Health Check: Automatic validation of database connectivity on startup

Supported Databases

Deployment Options

The DB MCP Server can be deployed in multiple ways to suit different environments and integration needs:

Docker Deployment

# Pull the latest image
docker pull freepeak/db-mcp-server:latest
 
# Run with mounted config file
docker run -p 9092:9092 \
  -v $(pwd)/config.json:/app/my-config.json \
  -e TRANSPORT_MODE=sse \
  -e CONFIG_PATH=/app/my-config.json \
  freepeak/db-mcp-server

Note: Mount to /app/my-config.json as the container has a default file at /app/config.json.

STDIO Mode (IDE Integration)

# Run the server in STDIO mode
./bin/server -t stdio -c config.json

For Cursor IDE integration, add to .cursor/mcp.json:

{
  "mcpServers": {
    "stdio-db-mcp-server": {
      "command": "/path/to/db-mcp-server/server",
      "args": ["-t", "stdio", "-c", "/path/to/config.json"]
    }
  }
}

SSE Mode (Server-Sent Events)

# Default configuration (localhost:9092)
./bin/server -t sse -c config.json
 
# Custom host and port
./bin/server -t sse -host 0.0.0.0 -port 8080 -c config.json

Client connection endpoint: http://localhost:9092/sse

Source Code Installation

# Clone the repository
git clone https://github.com/FreePeak/db-mcp-server.git
cd db-mcp-server
 
# Build the server
make build
 
# Run the server
./bin/server -t sse -c config.json

Configuration

Database Configuration File

Create a config.json file with your database connections:

{
  "connections": [
    {
      "id": "mysql1",
      "type": "mysql",
      "host": "mysql1",
      "port": 3306,
      "name": "db1",
      "user": "user1",
      "password": "password1",
      "query_timeout": 60,
      "max_open_conns": 20,
      "max_idle_conns": 5,
      "conn_max_lifetime_seconds": 300,
      "conn_max_idle_time_seconds": 60
    },
    {
      "id": "postgres1",
      "type": "postgres",
      "host": "postgres1",
      "port": 5432,
      "name": "db1",
      "user": "user1",
      "password": "password1"
    },
    {
      "id": "sqlite_app",
      "type": "sqlite",
      "database_path": "./data/app.db",
      "journal_mode": "WAL",
      "cache_size": 2000,
      "read_only": false,
      "use_modernc_driver": true,
      "query_timeout": 30,
      "max_open_conns": 1,
      "max_idle_conns": 1
    },
    {
      "id": "sqlite_encrypted",
      "type": "sqlite",
      "database_path": "./data/secure.db",
      "encryption_key": "your-secret-key-here",
      "journal_mode": "WAL",
      "use_modernc_driver": false
    },
    {
      "id": "sqlite_memory",
      "type": "sqlite",
      "database_path": ":memory:",
      "cache_size": 1000,
      "use_modernc_driver": true
    }
  ]
}

Command-Line Options

# Basic syntax
./bin/server -t <transport> -c <config-file>
 
# SSE transport options
./bin/server -t sse -host <hostname> -port <port> -c <config-file>
 
# Lazy loading mode (recommended for 10+ databases)
./bin/server -t stdio -c <config-file> --lazy-loading
 
# Customize log directory (useful for multi-project setups)
./bin/server -t stdio -c <config-file> -log-dir /tmp/db-mcp-logs
 
# Inline database configuration
./bin/server -t stdio -db-config '{"connections":[...]}'
 
# Environment variable configuration
export DB_CONFIG='{"connections":[...]}'
./bin/server -t stdio

Available Flags:

• -t, -transport: Transport mode (stdio or sse)
• -c, -config: Path to database configuration file
• -p, -port: Server port for SSE mode (default: 9092)
• -h, -host: Server host for SSE mode (default: localhost)
• -log-level: Log level (debug, info, warn, error)
• -log-dir: Directory for log files (default: ./logs in current directory)
• -db-config: Inline JSON database configuration

SQLite Configuration Options

When using SQLite databases, you can leverage these additional configuration options:

SQLite Connection Parameters

SQLite Examples

Basic File Database

{
  "id": "my_sqlite_db",
  "type": "sqlite",
  "database_path": "./data/myapp.db",
  "journal_mode": "WAL",
  "cache_size": 2000
}

Encrypted Database (SQLCipher)

{
  "id": "encrypted_db",
  "type": "sqlite",
  "database_path": "./data/secure.db",
  "encryption_key": "your-secret-encryption-key",
  "use_modernc_driver": false
}

In-Memory Database

{
  "id": "memory_db",
  "type": "sqlite",
  "database_path": ":memory:",
  "cache_size": 1000
}

Read-Only Database

{
  "id": "reference_data",
  "type": "sqlite",
  "database_path": "./data/reference.db",
  "read_only": true,
  "journal_mode": "DELETE"
}

Oracle Configuration Options

When using Oracle databases, you can leverage these additional configuration options:

Oracle Connection Parameters

Oracle Examples

Basic Oracle Connection (Development)

{
  "id": "oracle_dev",
  "type": "oracle",
  "host": "localhost",
  "port": 1521,
  "service_name": "XEPDB1",
  "user": "testuser",
  "password": "testpass",
  "max_open_conns": 50,
  "max_idle_conns": 10,
  "conn_max_lifetime_seconds": 1800
}

Oracle with SID (Legacy)

{
  "id": "oracle_legacy",
  "type": "oracle",
  "host": "oracledb.company.com",
  "port": 1521,
  "sid": "ORCL",
  "user": "app_user",
  "password": "app_password"
}

Oracle Cloud Autonomous Database (with Wallet)

{
  "id": "oracle_cloud",
  "type": "oracle",
  "user": "ADMIN",
  "password": "your-cloud-password",
  "wallet_location": "/path/to/wallet_DBNAME",
  "service_name": "dbname_high"
}

Oracle RAC (Real Application Clusters)

{
  "id": "oracle_rac",
  "type": "oracle",
  "host": "scan.company.com",
  "port": 1521,
  "service_name": "production",
  "user": "app_user",
  "password": "app_password",
  "max_open_conns": 100,
  "max_idle_conns": 20
}

Oracle with TNS Entry

{
  "id": "oracle_tns",
  "type": "oracle",
  "tns_admin": "/opt/oracle/network/admin",
  "tns_entry": "PROD_DB",
  "user": "app_user",
  "password": "app_password"
}

Oracle with Edition-Based Redefinition

{
  "id": "oracle_ebr",
  "type": "oracle",
  "host": "oracledb.company.com",
  "port": 1521,
  "service_name": "production",
  "user": "app_user",
  "password": "app_password",
  "edition": "v2_0"
}

Oracle Connection String Priority

When multiple connection methods are configured, the following priority is used:

1. TNS Entry (if tns_entry and tns_admin are configured)
2. Wallet (if wallet_location is configured) - for Oracle Cloud
3. Standard (host:port/service_name) - default method

Available Tools

For each connected database, DB MCP Server automatically generates these specialized tools:

Query Tools

Schema Tools

Performance Tools

TimescaleDB Tools

For PostgreSQL databases with TimescaleDB extension, these additional specialized tools are available:

For detailed documentation on TimescaleDB tools, see TIMESCALEDB_TOOLS.md.

Examples

Querying Multiple Databases

-- Query the MySQL database
query_mysql1("SELECT * FROM users LIMIT 10")
 
-- Query the PostgreSQL database in the same context
query_postgres1("SELECT * FROM products WHERE price > 100")
 
-- Query the SQLite database
query_sqlite_app("SELECT * FROM local_data WHERE created_at > datetime('now', '-1 day')")
 
-- Query the Oracle database
query_oracle_dev("SELECT * FROM employees WHERE hire_date > SYSDATE - 30")

Managing Transactions

-- Start a transaction
transaction_mysql1("BEGIN")
 
-- Execute statements within the transaction
execute_mysql1("INSERT INTO orders (customer_id, product_id) VALUES (1, 2)")
execute_mysql1("UPDATE inventory SET stock = stock - 1 WHERE product_id = 2")
 
-- Commit or rollback
transaction_mysql1("COMMIT")
-- OR
transaction_mysql1("ROLLBACK")

Exploring Database Schema

-- Get all tables in the database
schema_mysql1("tables")
 
-- Get columns for a specific table
schema_mysql1("columns", "users")
 
-- Get constraints
schema_mysql1("constraints", "orders")

Working with SQLite-Specific Features

-- Create a table in SQLite
execute_sqlite_app("CREATE TABLE IF NOT EXISTS local_cache (key TEXT PRIMARY KEY, value TEXT, timestamp DATETIME)")
 
-- Use SQLite-specific date functions
query_sqlite_app("SELECT * FROM events WHERE date(created_at) = date('now')")
 
-- Query SQLite master table for schema information
query_sqlite_app("SELECT name, sql FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'")
 
-- Performance optimization with WAL mode
execute_sqlite_app("PRAGMA journal_mode = WAL")
execute_sqlite_app("PRAGMA synchronous = NORMAL")

Working with Oracle-Specific Features

-- Query user tables (excludes system schemas)
query_oracle_dev("SELECT table_name FROM user_tables ORDER BY table_name")
 
-- Use Oracle-specific date functions
query_oracle_dev("SELECT employee_id, hire_date FROM employees WHERE hire_date >= TRUNC(SYSDATE, 'YEAR')")
 
-- Oracle sequence operations
execute_oracle_dev("CREATE SEQUENCE emp_seq START WITH 1000 INCREMENT BY 1")
query_oracle_dev("SELECT emp_seq.NEXTVAL FROM DUAL")
 
-- Oracle-specific data types
query_oracle_dev("SELECT order_id, TO_CHAR(order_date, 'YYYY-MM-DD HH24:MI:SS') FROM orders")
 
-- Get schema metadata from Oracle data dictionary
query_oracle_dev("SELECT column_name, data_type, nullable FROM user_tab_columns WHERE table_name = 'EMPLOYEES'")
 
-- Use Oracle analytic functions
query_oracle_dev("SELECT employee_id, salary, RANK() OVER (ORDER BY salary DESC) as salary_rank FROM employees")

Troubleshooting

Common Issues

• Connection Failures: Verify network connectivity and database credentials
• Permission Errors: Ensure the database user has appropriate permissions
• Timeout Issues: Check the query_timeout setting in your configuration

Logs

Enable verbose logging for troubleshooting:

./bin/server -t sse -c config.json -v

Testing

Running Tests

The project includes comprehensive unit and integration tests for all supported databases.

Unit Tests

Run unit tests (no database required):

make test
# or
go test -short ./...

Integration Tests

Integration tests require running database instances. We provide Docker Compose configurations for easy setup.

Test All Databases:

# Start test databases
docker-compose -f docker-compose.test.yml up -d
 
# Run all integration tests
go test ./... -v
 
# Stop test databases
docker-compose -f docker-compose.test.yml down -v

Test Oracle Database:

# Start Oracle test environment
./oracle-test.sh start
 
# Run Oracle tests
./oracle-test.sh test
# or manually
ORACLE_TEST_HOST=localhost go test -v ./pkg/db -run TestOracle
ORACLE_TEST_HOST=localhost go test -v ./pkg/dbtools -run TestOracle
 
# Stop Oracle test environment
./oracle-test.sh stop
 
# Full cleanup (removes volumes)
./oracle-test.sh cleanup

Test TimescaleDB:

# Start TimescaleDB test environment
./timescaledb-test.sh start
 
# Run TimescaleDB tests
TIMESCALEDB_TEST_HOST=localhost go test -v ./pkg/db/timescale ./internal/delivery/mcp
 
# Stop TimescaleDB test environment
./timescaledb-test.sh stop

Regression Tests

Run comprehensive regression tests across all database types:

# Ensure all test databases are running
docker-compose -f docker-compose.test.yml up -d
./oracle-test.sh start
 
# Run regression tests
MYSQL_TEST_HOST=localhost \
POSTGRES_TEST_HOST=localhost \
ORACLE_TEST_HOST=localhost \
go test -v ./pkg/db -run TestRegression
 
# Run connection pooling tests
go test -v ./pkg/db -run TestConnectionPooling

Continuous Integration

All tests run automatically on every pull request via GitHub Actions. The CI pipeline includes:

• Unit Tests: Fast tests that don't require database connections
• Integration Tests: Tests against MySQL, PostgreSQL, SQLite, and Oracle databases
• Regression Tests: Comprehensive tests ensuring backward compatibility
• Linting: Code quality checks with golangci-lint

Contributing

We welcome contributions to the DB MCP Server project! To contribute:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'feat: add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Please see our CONTRIBUTING.md file for detailed guidelines.

Testing Your Changes

Before submitting a pull request, please ensure:

1. All unit tests pass: go test -short ./...
2. Integration tests pass for affected databases
3. Code follows the project's style guidelines: golangci-lint run ./...
4. New features include appropriate test coverage

License

This project is licensed under the MIT License - see the LICENSE file for details.