ChrisGVE/localdata-mcp

LocalData MCP Server

A powerful, secure MCP server for local databases and structured text files with advanced security features and large dataset handling.

✨ Features

🗄️ Multi-Database Support

• SQL Databases: PostgreSQL, MySQL, SQLite
• Document Databases: MongoDB
• Structured Files: CSV, JSON, YAML, TOML

🔒 Advanced Security

• Path Security: Restricts file access to current working directory only
• SQL Injection Prevention: Parameterized queries and safe table identifiers
• Connection Limits: Maximum 10 concurrent database connections
• Input Validation: Comprehensive validation and sanitization

📊 Large Dataset Handling

• Query Buffering: Automatic buffering for results with 100+ rows
• Large File Support: 100MB+ files automatically use temporary SQLite storage
• Chunk Retrieval: Paginated access to large result sets
• Auto-Cleanup: 10-minute expiry with file modification detection

🛠️ Developer Experience

• Comprehensive Tools: 12 database operation tools
• Error Handling: Detailed, actionable error messages
• Thread Safety: Concurrent operation support
• Backward Compatible: All existing APIs preserved

🚀 Quick Start

Installation

# Using pip
pip install localdata-mcp

# Using uv (recommended)
uv tool install localdata-mcp

# Development installation
git clone https://github.com/ChrisGVE/localdata-mcp.git
cd localdata-mcp
pip install -e .

Configuration

Add to your MCP client configuration:

{
  "mcpServers": {
    "localdata": {
      "command": "localdata-mcp",
      "env": {}
    }
  }
}

Usage Examples

Connect to Databases

# PostgreSQL
connect_database("analytics", "postgresql", "postgresql://user:pass@localhost/db")

# SQLite
connect_database("local", "sqlite", "./data.sqlite")

# CSV Files
connect_database("csvdata", "csv", "./data.csv")

# JSON Files  
connect_database("config", "json", "./config.json")

Query Data

# Execute queries with automatic result formatting
execute_query("analytics", "SELECT * FROM users LIMIT 50")

# Large result sets use buffering automatically
execute_query_json("analytics", "SELECT * FROM large_table")

Handle Large Results

# Get chunked results for large datasets
get_query_chunk("analytics_1640995200_a1b2", 101, "100")

# Check buffer status
get_buffered_query_info("analytics_1640995200_a1b2")

# Manual cleanup
clear_query_buffer("analytics_1640995200_a1b2")

🔧 Available Tools

📋 Supported Data Sources

SQL Databases

• PostgreSQL: Full support with connection pooling
• MySQL: Complete MySQL/MariaDB compatibility
• SQLite: Local file and in-memory databases

Document Databases

• MongoDB: Collection queries and aggregation

Structured Files

• CSV: Large file automatic SQLite conversion
• JSON: Nested structure flattening
• YAML: Configuration file support
• TOML: Settings and config files

🛡️ Security Features

Path Security

# ✅ Allowed - current directory and subdirectories
"./data/users.csv"
"data/config.json" 
"subdir/file.yaml"

# ❌ Blocked - parent directory access
"../etc/passwd"
"../../sensitive.db"
"/etc/hosts"

SQL Injection Prevention

# ✅ Safe - parameterized queries
describe_table("mydb", "users")  # Validates table name

# ❌ Blocked - malicious input
describe_table("mydb", "users; DROP TABLE users; --")

Resource Limits

• Connection Limit: Maximum 10 concurrent connections
• File Size Threshold: 100MB triggers temporary storage
• Query Buffering: Automatic for 100+ row results
• Auto-Cleanup: Buffers expire after 10 minutes

📊 Performance & Scalability

Large File Handling

• Files over 100MB automatically use temporary SQLite storage
• Memory-efficient streaming for large datasets
• Automatic cleanup of temporary files

Query Optimization

• Results with 100+ rows automatically use buffering system
• Chunk-based retrieval for large datasets
• File modification detection for cache invalidation

Concurrency

• Thread-safe connection management
• Concurrent query execution support
• Resource pooling and limits

🧪 Testing & Quality

✅ 100% Test Coverage

• 100+ comprehensive test cases
• Security vulnerability testing
• Performance benchmarking
• Edge case validation

🔒 Security Validated

• Path traversal prevention
• SQL injection protection
• Resource exhaustion testing
• Malicious input handling

⚡ Performance Tested

• Large file processing
• Concurrent connection handling
• Memory usage optimization
• Query response times

🔄 API Compatibility

All existing MCP tool signatures remain 100% backward compatible. New functionality is additive only:

• ✅ All original tools work unchanged
• ✅ Enhanced responses with additional metadata
• ✅ New buffering tools for large datasets
• ✅ Improved error messages and validation

📖 Examples

Basic Database Operations

# Connect to SQLite
connect_database("sales", "sqlite", "./sales.db")

# Explore structure
describe_database("sales")
describe_table("sales", "orders")

# Query data
execute_query("sales", "SELECT product, SUM(amount) FROM orders GROUP BY product")

Large Dataset Processing

# Connect to large CSV
connect_database("bigdata", "csv", "./million_records.csv")

# Query returns buffer info for large results
result = execute_query_json("bigdata", "SELECT * FROM data WHERE category = 'A'")

# Access results in chunks
chunk = get_query_chunk("bigdata_1640995200_a1b2", 1, "1000")

Multi-Database Analysis

# Connect multiple sources
connect_database("postgres", "postgresql", "postgresql://localhost/prod")
connect_database("config", "yaml", "./config.yaml")
connect_database("logs", "json", "./logs.json")

# Query across sources (in application logic)
user_data = execute_query("postgres", "SELECT * FROM users")
config = read_text_file("./config.yaml", "yaml")

🚧 Roadmap

• Enhanced File Formats: Excel, Parquet support
• Caching Layer: Configurable query result caching
• Connection Pooling: Advanced connection management
• Streaming APIs: Real-time data processing
• Monitoring Tools: Connection and performance metrics

🤝 Contributing

Contributions welcome! Please read our for details.

Development Setup

git clone https://github.com/ChrisGVE/localdata-mcp.git
cd localdata-mcp
python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate
pip install -e ".[dev]"
pytest

📄 License

MIT License - see the file for details.

🔗 Links

• GitHub: localdata-mcp
• PyPI: localdata-mcp
• MCP Protocol: Model Context Protocol
• FastMCP: FastMCP Framework

📊 Stats

📚 Additional Resources

• : Common questions and troubleshooting
• : Comprehensive problem resolution
• : Production-ready usage patterns
• : Technical deep dive and use cases

🤔 Need Help?

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Email: Available in GitHub profile
• Community: Join MCP community forums

🏷️ Tags

mcp model-context-protocol database postgresql mysql sqlite mongodb csv json yaml toml ai machine-learning data-integration python security performance

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