TiDB vs WatermelonDB: What are the differences?

### Introduction
This markdown provides a comparison between TiDB and WatermelonDB focusing on the key differences between both database management systems.

1. **Data Model**: TiDB is a distributed SQL database that uses the traditional relational data model, while WatermelonDB is a mobile-first database designed to provide a seamless offline experience for mobile apps by using a normalized relational database model that is optimized for performance on mobile devices.

2. **Architecture**: TiDB follows a distributed architecture with a horizontally scalable, cloud-native design that supports high availability and strong consistency across clusters. On the other hand, WatermelonDB is specifically designed for offline-first applications, utilizing SQLite under the hood and a client-side database engine to interact with data locally on the device.

3. **Use Cases**: TiDB is suitable for large-scale, high-performance scenarios where distributed transactions and real-time analytics are required. WatermelonDB, on the other hand, is ideal for mobile applications that need to store and query data offline, offering fast read and write operations with minimal latency, making it suitable for mobile devices with limited processing power and network connectivity.

4. **Language Support**: TiDB supports SQL queries for interacting with the database, making it compatible with a wide range of existing applications and tools built around SQL. In contrast, WatermelonDB offers a high-level Query API that abstracts away SQL complexity, providing a more developer-friendly approach for managing data within a mobile app.

5. **Performance and Scalability**: TiDB is optimized for high performance and scalability, supporting sharding and partitioning to distribute data across multiple nodes in a cluster. WatermelonDB, while efficient for offline data handling on mobile devices, may have limitations in terms of performance and scalability when dealing with large datasets or complex queries due to its focus on local data synchronization.

6. **Community and Ecosystem**: TiDB has a larger open-source community and ecosystem, with support for various integrations, extensions, and tools to enhance its functionality and usability. In comparison, WatermelonDB, being more specialized for mobile app development, has a smaller but active community focused on improving the library for offline data management in mobile applications.

In Summary, TiDB is a distributed SQL database built for high-performance, scalable applications, while WatermelonDB is a mobile-first database optimized for offline data storage and retrieval in mobile apps. Each database system has its unique strengths and is tailored to different use cases and environments.