TiDB

TiDB is the distributed SQL database that lets you scale MySQL horizontally without changing your application code. MySQL-compatible wire protocol, HTAP (real-time analytics on transactional data), and automatic sharding. It's Google Spanner's architecture, open-sourced.

If you've outgrown a single MySQL instance and need horizontal scaling with strong consistency, TiDB is the MySQL-ecosystem answer. CockroachDB does the same for PostgreSQL. YugabyteDB supports both protocols. Vitess (from YouTube) shards MySQL but requires more application awareness. Commercially, Aurora and Cloud Spanner are the managed distributed SQL options.

The HTAP story is compelling: TiKV handles OLTP, TiFlash handles OLAP, and they replicate in real-time. No ETL pipeline from production to analytics warehouse.

The catch: running TiDB in production means operating a distributed system with multiple components (TiDB, TiKV, PD, optionally TiFlash). That's a significant ops burden for small teams. Performance for simple OLTP queries won't match a well-tuned single-node MySQL. And if you don't actually need horizontal scaling, a single Postgres instance with read replicas is simpler and cheaper.