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This article mainly explains "the main features, advantages and disadvantages of MySQL NDB Cluster and Galera Cluster". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "the main features, advantages and disadvantages of MySQL NDB Cluster and Galera Cluster".

MySQL NDB Cluster is a highly practical and highly redundant version of MySQL suitable for distributed computing environments. It uses the NDB Cluster storage engine, which allows multiple MySQL servers to run in one Cluster.

MySQL NDB Cluster is a technology that allows you to deploy the Cluster of an "in-memory" database in a system without sharing. Through the non-shared architecture, the system can use cheap hardware, and there are no special requirements for hardware and software. In addition, because each component has its own memory and disk, there is no single point of failure.

MySQL NDB cluster consists of three main types of services:

NDB Management Server: the management server is mainly used to manage other types of nodes in the cluster (Data Node and SQL Node), through which you can configure Node information and start and stop Node.

SQL Node: in MySQL Cluster, a SQL Node is a mysql server process that uses the NDB engine to provide access to cluster data for external applications.

Data Node: used to store cluster data; the system will try to keep the data in memory.

Advantages:

1. Achieve a high level of write scalability through automatic sharding

MySQL Cluster automatically fragments (or partitions) tables to different nodes, allowing databases to scale out on low-cost commercial hardware while maintaining complete transparency to applications.

2.99.999% availability

With its distributed, no-shared architecture, MySQL Cluster provides 99.999% availability, ensuring strong fault resilience and the ability to perform scheduled maintenance without downtime.

3.SQL and NoSQL API

MySQL Cluster allows users to integrate the best parts of relational database technology and NoSQL technology into the solution, thereby reducing cost, risk, and complexity.

4. Real-time performance

MySQL Cluster provides real-time response time and throughput to meet the most demanding needs of Web, telecom, and enterprise applications.

5. Multi-site cluster with cross-regional replication function

Cross-regional replication enables multiple clusters to be distributed in different locations, thus improving disaster recovery and global Web service scalability.

6. Online expansion and mode upgrade

To support ongoing operations, MySQL Cluster allows you to add nodes and update content online to a running database schema, thus supporting rapidly changing and highly dynamic loads.

Disadvantages:

1. Based on memory, the size of the database is limited by the total memory of the cluster.

two。 Multiple nodes realize communication, data synchronization, query and other operations through the network, so the integrity is affected by the network speed.

3. For tables that need to be sharded, you need to modify the engine Innodb to NDB, and those that do not need sharding do not need to be modified.

4.NDB 's transaction isolation level only supports Read Committed, that is, a transaction cannot query changes made within a transaction before committing, while Innodb supports all transaction isolation levels and defaults to Repeatable Read, which does not exist.

5. Foreign key support: although the latest version of Cluster already supports foreign keys, there is a performance problem (because the records associated with foreign keys may be in other shard nodes), so it is recommended to remove all foreign keys.

6.Data Node node data will be kept in memory as much as possible, which requires a lot of memory.

Advantages and disadvantages of Mysql-cluster

Advantages:

A) there are many restrictions, such as: foreign keys are not supported, data rows cannot exceed 8K (excluding data in BLOB and text)

B) deployment, management and configuration are complex

C) large disk space and large memory

D) inconvenient backup and recovery

E) when rebooting, it takes a long time for the data node to load the data to memory

Galera Cluster for MySQL is a multi-master MySQL cluster solution based on synchronous replication, which is easy to use, no single point of failure, and high availability. It can ensure the security of our data and expand at any time when the business is growing. It is known as the most advanced open source database cluster solution in the world.

The main features and characteristics are as follows:

1. Support for InnoDB engine

two。 Synchronous replication, no delay between nodes and no data loss due to node downtime

3. Topology of multi-master server

4. You can read and write on any node

5. Automatic elimination of fault nodes

6. Automatic identity control, failed nodes automatically break away from the cluster

7. Automatically add a new node

8. True row-level concurrent replication

9. Client connection is consistent with the experience of operating a single MySQL database, transparent to the application, and does not need to be modified.

10. Hot Standby with no downtime during Failover (due to no need for Failover)

11. Automatic node configuration without manually backing up the current database and copying it to the new node

twelve。 Corresponding to transparency, no need to change the application or make minimal changes

13. There is no need for read-write separation

14. True parallel replication based on "row" level and ID check

Thank you for your reading, the above is the content of "the main features and advantages and disadvantages of MySQL NDB Cluster and Galera Cluster". After the study of this article, I believe you have a deeper understanding of the main characteristics, advantages and disadvantages of MySQL NDB Cluster and Galera Cluster, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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