What are the data sharding and data isolation techniques for learning MySQL?

What are the data sharding and data isolation techniques for learning MySQL?

Data sharding and data isolation are common technical means in MySQL databases, which are used to solve problems such as excessive data volume and heavy load. This article will introduce commonly used data sharding and data isolation techniques in MySQL, and attach code examples.

1. Data sharding skills

1. Vertical sharding: Separate the tables in the database according to functional modules, store different functional modules in different databases, and use Foreign keys establish associations. The sample code is as follows:

-- 创建用户表
CREATE TABLE user (
   id INT(11) PRIMARY KEY,
   username VARCHAR(50),
   password VARCHAR(50)
) ENGINE=InnoDB;

-- 创建订单表
CREATE TABLE order (
   id INT(11) PRIMARY KEY,
   user_id INT(11),
   product_id INT(11),
   amount INT(11),
   FOREIGN KEY (user_id) REFERENCES user(id)
) ENGINE=InnoDB;

2. Horizontal sharding: Split the table in the database according to a certain field and evenly distribute the data to multiple databases. The sample code is as follows:

-- 创建用户表
CREATE TABLE user_0 (
   id INT(11) PRIMARY KEY,
   username VARCHAR(50),
   password VARCHAR(50)
) ENGINE=InnoDB;

-- 创建用户表
CREATE TABLE user_1 (
   id INT(11) PRIMARY KEY,
   username VARCHAR(50),
   password VARCHAR(50)
) ENGINE=InnoDB;

-- 创建订单表
CREATE TABLE order_0 (
   id INT(11) PRIMARY KEY,
   user_id INT(11),
   product_id INT(11),
   amount INT(11)
) ENGINE=InnoDB;

-- 创建订单表
CREATE TABLE order_1 (
   id INT(11) PRIMARY KEY,
   user_id INT(11),
   product_id INT(11),
   amount INT(11)
) ENGINE=InnoDB;

3. Sharding key selection: Choosing the appropriate sharding key can improve query performance. Fields with high cardinality are usually chosen as sharding keys, such as user ID or order ID.

2. Data isolation skills

1. Transaction isolation level: Control the degree of data isolation by setting the isolation level of the transaction. Commonly used transaction isolation levels include READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ and SERIALIZABLE.

-- 设置事务隔离级别为读取提交
SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;

2. Row-level locks: When operating data, row-level locks can be used to ensure data isolation and avoid problems caused by concurrent operations.

-- 开启事务
START TRANSACTION;

-- 锁定行级别
SELECT * FROM user WHERE id = 1 FOR UPDATE;

-- 更新数据
UPDATE user SET username = 'new_username' WHERE id = 1;

-- 提交事务
COMMIT;

3. Database isolation: Store different business data in different databases, and achieve data isolation by controlling the access permissions of different databases. The sample code is as follows:

-- 创建业务数据库1
CREATE DATABASE business_1;

-- 给用户赋予业务数据库1的访问权限
GRANT ALL PRIVILEGES ON business_1.* TO 'user'@'%' IDENTIFIED BY 'password';

-- 创建业务数据库2
CREATE DATABASE business_2;

-- 给用户赋予业务数据库2的访问权限
GRANT ALL PRIVILEGES ON business_2.* TO 'user'@'%' IDENTIFIED BY 'password';

Summary

This article introduces the commonly used data sharding and data isolation techniques in MySQL, and gives corresponding code examples. Data sharding divides the database into multiple modules through vertical sharding and horizontal sharding to improve database performance and scalability; data isolation ensures data isolation through transaction isolation levels, row-level locks and database isolation. In actual applications, appropriate sharding and isolation methods need to be selected based on business needs.

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