foreword

In modern database architecture, MySQL master-slave replication technology plays an important role. It can not only improve database performance and scalability, but also endow the system with excellent high availability and disaster recovery capabilities. This article will deeply analyze the internal mechanism of MySQL master-slave replication, and at the same time demonstrate its powerful role in actual scenarios through a practical case.

core mechanism

MySQL master-slave replication is based on binary log (Binary Log) technology, and its core process is as follows:

Recording of the main database: The main database records all write operations in the binary log, creating a series of binary log events.
Connection from the database: connect to the master database from the database, and request to obtain its binary log events.
Playback from the database: The binary log events received are played back sequentially from the database to simulate performing the same write operations as the primary database.
Relay from the database: Create a relay log from the database to record the operations performed by itself.
Read service from the database: accept the read request from the application program from the database, and process and respond to it.

Example demo

To better understand MySQL master-slave replication, we'll show how it works through a concise example. Suppose there is an e-commerce website, where the master database handles write operations and the slave database is used for read operations.

Step 1: Master Database Configuration

First, we enable binary logging on the primary database, then create a user for replication. Execute the following commands in the MySQL master database:

Open the MySQL configuration file for the master databasemy.ini
Enable binary logging:log_bin = mysql-bin
Set the unique ID of the master server:server_id = 1
Restart the primary database for the configuration to take effect.

Step 2: Create a replication user

Connect to the primary database and create a replication user:

CREATE USER 'replication_user'@'%' IDENTIFIED BY 'password';

Grant copy permission:

GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'replication_user'@'%';

Step 3: Back up the master database

mysqldumpBack up the master server's database using an appropriate backup tool such as .

Step 4: Get primary database status information

Connect to the main database, run: SHOW MASTER STATUS;, and record the values of Fileand Position.

SHOW MASTER STATUS;

Step 5: Configure from database

mysqldumpBack up the master server's database using an appropriate backup tool such as .
Open the MySQL configuration file from the databasemy.ini
Set the unique ID of the master server:server_id = 2
Restart the primary database for the configuration to take effect.

Step 6: Set up replication from the database

To connect to the slave database, run:

CHANGE MASTER TO
MASTER_HOST = '主数据库IP地址',
MASTER_USER = 'replication_user',
MASTER_PASSWORD = 'password',
MASTER_LOG_FILE = '主数据库的日志文件名',
MASTER_LOG_POS = '主数据库的日志位置';

Step 7: Start copying from the database

To connect to the slave database, run:

START SLAVE;

Step 8: Test master-slave replication

Now, we perform some write operations on the master database, and then confirm that the replication was successful on the slave database. For example, to insert data into the main database:

INSERT INTO products (name, price) VALUES ('新商品', 99.99);

Next, query from the database:

SELECT * FROM products;

You should see the new item just inserted, indicating that master-slave replication has run successfully.

Notes and Answers

When implementing MySQL master-slave replication, please pay attention to the following items and provide corresponding answers:

Q1: Will master-slave replication affect performance?

Answer: The master-slave replication will affect the performance of the master database to a certain extent, because the write operation needs to record the binary log and transmit it to the slave database. However, slaves can offload read requests, improving overall performance. If the write load of the primary database is too large, master-slave replication can be used to alleviate it.

Q2: Will there be a delay in master-slave replication?

Answer: Yes, there may be a certain delay in the master-slave replication, because the slave database needs to wait for the master database to record and transmit the binary log. This can have implications for applications that require real-time data synchronization. To address this issue, consider synchronous replication or other data synchronization strategies.

Q3: How to ensure high availability of master-slave replication?

Answer: To ensure high availability, multiple slave databases can be configured to achieve hot backup of the master database. At the same time, combined with database cluster technologies such as MySQL Galera Cluster, Percona XtraDB Clusteretc., to improve availability.

Q4: How to monitor and maintain master-slave replication?

Answer: You can use SHOW SLAVE STATUScommands to monitor the replication status of the slave database. Periodically review the status to ensure that replication is functioning properly. In addition, regularly back up and restore the slave database to ensure data integrity.

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Guide to High Availability Architecture Based on Binary Logs for MySQL Master-Slave Replication