# Sample Architecture without TiDB

![left](./student-guide/diagram/ArchBeforeTiDB_en_001_20220721.png)

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MySQL for online transaction processing.

With the read-replicas, we can now handle a pretty serious load. 

Cache for transit session level object to improve performance.

NoSQL for horizontal scalable persistent store and SQL incompatible.  

The data layer architecture is complicated to some extents.