MySQL Cluster is more suitable for high concurrency and low latency scenarios, and uses a distributed architecture to support data sharding and fast failover; Group Replication emphasizes data consistency, which is suitable for scenarios with high consistency requirements, and implements multi-node synchronous replication based on Paxos. 1. MySQL Cluster adopts a shared-nothing architecture, supports automatic sharding and online expansion, which is suitable for telecommunications and real-time billing systems; 2. Group Replication saves complete data for each node, guarantees consistency through majority consensus, and is suitable for financial transaction systems; 3. Group Replication checks consistency before submission, and quickly selects the master in case of failure, while Cluster communicates asynchronously or semi-synchronously, with low latency but may be temporarily inconsistent; 4. Group Replication is simple to deploy but sensitive to network latency, and Cluster is complex to deploy and requires in-depth optimization; 5. If you pursue consistency and have weak operation and maintenance capabilities, choose Group Replication. If you have a strong technical team and need a high-performance scalable platform, choose Cluster.

MySQL Cluster and Group Replication are both highly available solutions provided by MySQL, but they vary significantly in architecture design, applicable scenarios and performance. If you are considering which solution to deploy to ensure the stability of your database service, you must first understand the core mechanisms and their respective advantages of these two technologies.

Different architecture principles determine the usage scenario

MySQL Cluster (NDB Cluster) is a distributed database system with shared-nothing architecture. It stores data fragments in multiple nodes and supports automatic failover and online expansion. Suitable for applications that require extremely high concurrent read and write and low latency response, such as telecommunications, real-time billing systems, etc.

Group Replication is a synchronous replication mechanism between a set of MySQL instances implemented based on the Paxos protocol. Each node saves a complete copy of the data and supports multi-write mode. It is suitable for business scenarios with high consistency requirements and moderate data volume, such as financial transaction systems.

Simply put:

• Cluster emphasizes distribution and expansion
• Group Replication emphasizes consistency and error tolerance

Data consistency and failure recovery mechanism are different

Group Replication will perform consistency verification before transaction submission to ensure that most nodes only submit after reaching consensus, thus providing stronger data consistency guarantees. Once a node fails, the cluster can quickly select a new master and continue to provide services.

MySQL Cluster uses asynchronous or semi-synchronous methods to handle cross-node communication. Although the overall delay is low, short-term data inconsistency may occur when network partitions or nodes are down. However, its automatic failover speed is very fast and can usually switch in seconds.

For example:
If your application cannot tolerate even a dirty read, Group Replication will be better for you; but if you value the continuous availability and high performance of the system, Cluster may be a better choice.

Performance and operation complexity have their own focus

Group Replication is relatively simple to deploy. You only need to configure the replication channel and group communication parameters of each node to start. However, it is more sensitive to network latency, especially in multi-write mode, which is prone to conflicts and causes transaction rollback.

Although MySQL Cluster is powerful, the threshold for deployment and tuning is high. You need to understand the contents of multiple levels such as data sharding strategy, memory management, node role division, etc. In addition, the NDB engine and traditional InnoDB have a large difference in behavior and the migration cost is not small.

A few suggestions:

• If you are pursuing out-of-the-box and have strict consistency requirements → Choose Group Replication
• If you have a strong technical team and want to build a high-performance, scalable database platform → try Cluster
• If your application has high write pressure and tolerate slight delay consistency → Cluster is more suitable

Basically that's it. Neither solution is omnipotent. The key to selection is to clarify one's business needs and technical capabilities.

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