MySQL vs TiDB: What are the differences?

Introduction

MySQL and TiDB are both popular databases used in web development. While MySQL is a traditional relational database management system, TiDB is a newer distributed SQL database built for scalability and high availability. However, there are key differences between the two that set them apart.

1. Data Placement: In MySQL, data is typically placed on a single server, whereas TiDB automatically splits and replicates data across multiple servers for better durability and fault tolerance. This allows TiDB to handle large amounts of data and provide high availability without manual sharding or partitioning.

2. Architecture: MySQL follows a master-slave replication model where a single master handles write operations and multiple slaves handle read operations. On the other hand, TiDB uses a distributed architecture based on the Google Spanner model, with multiple TiKV nodes and TiDB nodes working together to provide horizontal scalability and fault tolerance.

3. Consistency Model: MySQL follows the strong consistency model, where transactions are ACID-compliant and guarantee data integrity. In contrast, TiDB provides a unique consistency model called "consistency without consensus." It uses a distributed consensus algorithm to achieve linearizability, ensuring global consistency while still maintaining high availability and performance.

4. SQL Compatibility: MySQL has been around for a long time and has a wide range of SQL compatibility, including support for complex queries, stored procedures, and triggers. While TiDB also supports standard SQL, some advanced features and syntax are still in development or not yet available.

5. Scalability: MySQL can scale vertically by adding more resources to a single server, but it has limitations in terms of horizontal scalability. TiDB, on the other hand, is designed for horizontal scalability and can easily handle high traffic loads by adding more nodes to the cluster.

6. Fault Tolerance: In MySQL, fault tolerance is achieved through techniques like replication, failover, and backup/restore. TiDB, being a distributed system, has built-in fault tolerance mechanisms. It distributes data across multiple nodes, automatically replicates data, and can tolerate node failures without data loss.

In summary, MySQL and TiDB differ in terms of data placement, architecture, consistency model, SQL compatibility, scalability, and fault tolerance. While MySQL is a mature RDBMS with extensive SQL compatibility, TiDB offers scalability, fault tolerance, and consistency without consensus in a distributed SQL database system.