Explore why MySQL master-slave replication is classified as a cluster technology rather than a load balancing technology?

Explore why MySQL master-slave replication is classified as a cluster technology rather than a load balancing technology?

As a database replication technology, MySQL master-slave replication plays an important role in the database system. However, although master-slave replication can improve the performance and availability of the database system, it is classified as a cluster technology rather than a load balancing technology. Why? This article will delve into the nature of MySQL master-slave replication and give an explanation.

Before we begin, let’s review the concept of load balancing technology. Load balancing technology is designed to distribute workloads and balance requests on servers to achieve high availability and performance. It achieves load balancing by distributing requests to multiple servers and deciding the routing of requests based on performance indicators. Load balancing technology is suitable for a wide range of application scenarios, such as web servers, application servers, etc. However, in the MySQL database, load balancing technology is not suitable for master-slave replication.

So, why is MySQL master-slave replication classified as a cluster technology? Let’s first understand the concept of master-slave replication. MySQL master-slave replication refers to the process of copying data from one MySQL server (master server) to multiple other MySQL servers (slave servers). The master server is responsible for writing data operations and passing the written log to the slave server, and the slave server is responsible for reading data operations. In this way, master-slave replication realizes redundant backup of data and separation of reading and writing, improving the availability and performance of the database system.

The main difference compared to load balancing technology is that MySQL master-slave replication does not implement request allocation, nor does it make routing decisions on requests. The master server is still responsible for all write operations and passes update operations to the slave servers one by one. The slave server is only responsible for read operations, and the data synchronization between them is asynchronous. Therefore, unlike load balancing technology, which requires complex analysis and decision-making on requests, master-slave replication only needs to simply forward write operations to the slave server.

The following is a simple MySQL master-slave replication example code:

Master server configuration:

# my.cnf

server-id=1
log-bin=mysql-bin
binlog-do-db=mydb

Slave server configuration:

# my.cnf

server-id=2
relay-log=mysql-relay-bin

On the master server Perform the following operations:

-- 创建数据库和表
CREATE DATABASE mydb;
USE mydb;

CREATE TABLE employees (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50),
    age INT
);

-- 插入数据
INSERT INTO employees (name, age) VALUES ('Alice', 25);
INSERT INTO employees (name, age) VALUES ('Bob', 30);

The slave server will automatically synchronize the data on the master server and can perform read operations:

-- 从服务器上查询数据
USE mydb;
SELECT * FROM employees;

The above example shows the basic principle of MySQL master-slave replication. In practical applications, master-slave replication can also break through the physical limitations of the server and achieve distributed storage and processing of data. Of course, you can also combine load balancing technology on the basis of the master-slave architecture to achieve a database cluster with higher performance and higher availability.

To sum up, the reason why MySQL master-slave replication is classified as a cluster technology is because it mainly realizes redundant backup of data and separation of read and write, rather than realizing requests like load balancing technology. Apportionment and routing decisions. Despite this, master-slave replication still plays an important role in database systems, providing high availability and high performance support for applications.

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