The topic describes the technical architecture of PolarDB-X Standard Edition.
PolarDB-X Standard Edition integrates the centralized and integrated architectures. Each data node (DN) in the distributed architecture can deliver services independently. Moreover, it provides syntax and features that are fully compatible with MySQL, such as MySQL 5.7 and 8.0. PolarDB-X Standard Edition advances its features and elevates both its performance and high availability by using distributed technologies, making a substantial improvement over native MySQL.
Architecture
PolarDB-X Standard Edition adopts a layered architecture:
Log layer: uses the majority-based replication protocol of Paxos. Consensus logs of Paxos are compatible with MySQL binary logs. PolarDB-X Standard Edition can provide financial-grade disaster recovery with a recovery point objective (RPO) of 0, which guarantees zero data loss in case of a data center failure. This marks a substantial improvement over the MySQL master-slave replication protocol (binary log-based async replication or semi-sync replication).
Storage layer: The in-house Lizard transaction system interfaces with the log layer and can be used to replace the standalone InnoDB transaction system of MySQL. The SCN standalone transaction system and GCN distributed transaction system are designed to optimize centralized and distributed transactions. Moreover, based on the SCN standalone transaction system, PolarDB-X Standard Edition provides transaction isolation levels in line with MySQL standards.
Execution layer: is similar to the server layer of native MySQL. The in-house xRPC server can be used to access PolarDB-X Enterprise Edition to implement distributed queries. PolarDB-X Standard Edition provides this layer with SQL execution capabilities for compatibility with the server layer of native MySQL. It works with the transaction system at the storage layer for data processing.
PolarDB-X Standard Edition improves the centralized architecture by using the distributed technology. PolarDB-X Standard Edition is fully compatible with native MySQL and can be used as a substitute for open-source MySQL ecosystem. In 2023, PolarDB-X Standard Edition was open-sourced. For more information, see PolarDB-X Engine.