How to implement incremental update and synchronization of data in MySQL?

MySQL is one of the most commonly used relational database management systems, used to store and manage massive amounts of data. In practical applications, due to the frequent update and synchronization of data, the efficiency of data update and synchronization has become an important issue. This article will introduce how to implement incremental update and synchronization of data through MySQL, and provide code examples.

1. Data incremental update

1. The concept of incremental update

Data incremental update refers to updating only the changed data items, and All data will not be fully updated. This can reduce data transmission and processing overhead and improve the efficiency of data update.

2. Implementation method of incremental update

(1) Use timestamp or version number

Add a field indicating the update time in the data table , every time the data is updated, update this field to the current time. During incremental update, you only need to compare the difference between the current timestamp and the target timestamp, and then update the difference data.

The sample code is as follows:

-- 添加时间戳字段
ALTER TABLE table_name ADD COLUMN update_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP;

-- 增量更新
SELECT * FROM table_name WHERE update_time > '目标时间戳';

(2) Use the record change log

Add a log table to record the change operation in the data table. Each time the data is updated, Change operations are written to the log table. During incremental updates, you only need to read the change operations in the log table, and then update the target data accordingly.

The sample code is as follows:

-- 创建日志表
CREATE TABLE log_table (
    id INT AUTO_INCREMENT PRIMARY KEY,
    table_name VARCHAR(100),
    record_id INT,
    operation VARCHAR(10),
    update_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- 添加记录变更操作
INSERT INTO log_table (table_name, record_id, operation) VALUES ('table_name', record_id, 'update');

-- 增量更新
SELECT * FROM table_name WHERE id IN (SELECT record_id FROM log_table WHERE table_name = 'table_name' AND operation = 'update');

2. Data synchronization

1. The concept of data synchronization

Data synchronization refers to the synchronization of a database The process of copying data from a database to another database. Common application scenarios include master-slave replication, multi-master replication, etc.

2. How to implement data synchronization

(1) Master-slave replication

Master-slave replication refers to using one database as the master database and responsible for writing data and copies the data to one or more slave databases. The slave database is only responsible for reading data and does not perform writing operations. Master-slave replication can be achieved through MySQL's replication function.

The sample code is as follows:

Execute the following command on the master database:

-- 开启二进制日志
SET GLOBAL log_bin = ON;

-- 创建复制用户
CREATE USER 'repl' IDENTIFIED BY 'password';

-- 授予复制权限
GRANT REPLICATION SLAVE ON *.* TO 'repl';

-- 查看当前主数据库的状态
SHOW MASTER STATUS;

Execute the following command on the slave database:

-- 设置从数据库的复制参数
CHANGE MASTER TO 
    MASTER_HOST = '主数据库的IP地址',
    MASTER_USER = 'repl',
    MASTER_PASSWORD = 'password',
    MASTER_LOG_FILE = '主数据库的二进制日志文件名',
    MASTER_LOG_POS = 主数据库的二进制日志位置;

-- 开始复制
START SLAVE;

(2) More Master replication

Multi-master replication refers to using multiple databases as master databases at the same time to replicate data between each other. Multi-master replication can be achieved through MySQL's group replication feature.

The sample code is as follows:

Execute the following command on each master database:

-- 开启组复制
SET GLOBAL group_replication_bootstrap_group = ON;

-- 创建组复制用户
CREATE USER 'repl' IDENTIFIED BY 'password';

-- 授予组复制权限
GRANT REPLICATION SLAVE ON *.* TO 'repl';

-- 查看当前主数据库的状态
SHOW MASTER STATUS;

-- 结束组复制
SET GLOBAL group_replication_bootstrap_group = OFF;

Execute the following command on each slave database:

-- 设置从数据库的复制参数
SET GLOBAL group_replication_group_seeds = '主数据库1的IP地址:端口,主数据库2的IP地址:端口,...';

-- 开始复制
START GROUP_REPLICATION;

The above is the method to achieve incremental update and synchronization of data in MySQL. Through incremental updates, unnecessary data interaction and processing can be avoided; through data synchronization, data can be copied and shared between multiple databases. In practical applications, appropriate methods are selected according to specific needs and scenarios to achieve incremental updates and synchronization of data to improve database performance and reliability.

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