The elastic mode of AnalyticDB for MySQL utilizes an architecture that separates storage resources from computing resources. The storage layer still adopts the shared-nothing architecture that combines the scalability and concurrency of the reserved mode.
After a few processes are complete, data is written by frontend nodes of the AnalyticDB for MySQL access layer to the storage layer in real time. These processes include SQL parsing, validity verification, and partition selection. The storage layer adopts a three-replica architecture. These replicas are peers to one another. Data is synchronized among replicas by using a distributed consensus protocol. SQL query channels start from frontend nodes. After SQL parsing, optimization by optimizers, and task scheduling, distributed computing tasks are sent to the computing layer. Only index filtering and data scanning are performed at the storage layer. This completely isolates computing tasks with heavy query channels from storage nodes.