TiDB

TiDB (pronounced as Ti-DB, with Ti standing for Titanium) is an open-source, distributed, Hybrid Transactional and Analytical Processing (HTAP) database developed by PingCAP, a company founded in 2015 by Dong Qi, Ed Huang, and Ti Liu. TiDB is designed to combine the best of both worlds: the ACID transaction guarantees and SQL compatibility of traditional relational databases (like MySQL) with the horizontal scalability and high availability of distributed NoSQL databases (like Cassandra or MongoDB). This is achieved through a separation of compute and storage: the TiDB layer handles SQL parsing, query optimization, and transaction management, while the TiKV layer (a distributed key-value store built in Rust) handles data storage and replication. TiDB is fully MySQL-compatible at the wire protocol level, meaning existing MySQL applications and tools (including ORMs, migration tools, and GUI clients) can connect to TiDB without modification. Key architectural components include: TiDB Server (stateless SQL layer, can be scaled horizontally by adding more nodes), TiKV (distributed transactional key-value store using the Raft consensus algorithm for data replication and failover, storing data in Regions of approximately 96MB each), PD (Placement Driver, the cluster metadata manager responsible for data placement decisions and timestamp allocation for distributed transactions), and TiFlash (an optional columnar storage engine that enables real-time analytical queries on the same data, providing HTAP capabilities). TiDB supports online DDL operations (schema changes without downtime), cross-datacenter deployment for disaster recovery, global timestamps for distributed ACID transactions via a centralized TSO (Timestamp Oracle). As of 2026, TiDB has over 37,000 GitHub stars.