As a distributed database system, the highly-layered architecture of TiDB is not a disadvantage because it makes TiDB easier to debug and diagnose when issues occur. The complicity resulted from the separated modules can be easily tackled by automatic deployment tools and microservice framework.
For example, TiDB can be easily deployed either using Ansible: https://pingcap.com/docs/op-guide/ansible-deployment/
or Docker Compose:
https://pingcap.com/docs/op-guide/docker-compose/
TiDB has been widely adopted by many users (https://github.com/pingcap/docs/blob/master/adopters.md) in production because it support the best features of both RDBMS and NoSQL. It is quickly evolving and iterating based on users’ requirements which are prioritized and listed on the Roadmap.
Sure, I get the advantages of layers in architecture, especially the growing trend of separating compute and storage.
However there's a difference between architecture and deployment, and having everything in a single package makes operations much easier. CockroachDB also uses a KV storage layer (using RocksDB) with SQL on top.
TiKV uses Rocks also which is not distributed. TiKV is distributed and used by TiDB. TiSpark also uses TiKV directly which starts to demonstrate some of the advantages of the layered architecture.
I get it. Both databases are layered, but I'm saying deployment is still easier with a single package/binary instead of having TiDB, TiKV and Placement Driver instances.
TiDB provides many some ways to let the deployment easier. If you just want to have a try on the single machine, we provide docker-compose (https://github.com/pingcap/tidb-docker-compose). But if you don't like docker, the single binary may be easier.
For the business users, we support ansible and K8s deployment, both can help them run the TiDB easily and quickly in production. The deployment is not a problem so far.
IMO, for the distributed system, if you need to operate many instances (10, 100 or even more), what you pay attention to most is not whether the instance is one single binary or not, but is how to operate all these easily. At that time, there is no much difference.
TiDB has been widely adopted by many users (https://github.com/pingcap/docs/blob/master/adopters.md) in production because it support the best features of both RDBMS and NoSQL. It is quickly evolving and iterating based on users’ requirements which are prioritized and listed on the Roadmap.