Cassandra vs TiDB: What are the differences?
Introduction
Cassandra and TiDB are both highly scalable distributed databases designed to handle large amounts of data. However, there are several key differences between these two databases.
-
Consistency Model: Cassandra uses the eventual consistency model, where updates may take some time to propagate across all replicas, allowing for high availability and low latency. On the other hand, TiDB supports both the strong consistency model (ACID transactions) and the eventual consistency model, providing flexibility based on the use case.
-
Data Model: Cassandra follows a column-based data model, where data is stored in tables with partitions and rows. It can handle structured, semi-structured, and unstructured data. In contrast, TiDB follows a relational data model with tables, columns, and rows, similar to traditional SQL databases like MySQL.
-
Data Distribution: Cassandra employs a partition-centric model, distributing data across multiple nodes using a consistent hashing algorithm. Each node is responsible for a range of data partitions. In TiDB, data is distributed through a region-based model, where data is divided into regions that can be dynamically scheduled across multiple nodes. This approach allows automatic load balancing and better performance optimization.
-
Consistency and Availability Trade-off: Cassandra prioritizes availability over consistency, making it well-suited for use cases where high availability and low latency are crucial. TiDB, however, provides a balance between consistency and availability, making it suitable for applications that require strong consistency guarantees.
-
Scalability: Both Cassandra and TiDB are horizontally scalable databases that support distributed deployments. However, TiDB offers a more straightforward approach to scaling by enabling horizontal scaling of both compute and storage, while Cassandra requires manual tuning and cluster expansion to scale effectively.
-
Query Processing: Cassandra provides a query language called CQL (Cassandra Query Language), which is similar to SQL but has some differences in syntax and functionality. TiDB supports standard SQL queries and is fully compatible with the MySQL protocol, making it easy to migrate existing MySQL applications to TiDB without any code changes.
In summary, Cassandra and TiDB diverge in their consistency models, data models, data distribution strategies, consistency and availability trade-offs, scalability approaches, and query processing languages. While Cassandra prioritizes availability and eventual consistency, TiDB offers both strong consistency and eventual consistency, making it more versatile for different use cases.
