search
HomeDatabaseMysql TutorialMySQL transaction isolation level and concurrency control

MySQL transaction isolation level and concurrency control

Mar 01, 2024 pm 03:12 PM
mysqlaffairsconcurrentconcurrent access

MySQL transaction isolation level and concurrency control

Title: An in-depth discussion of the isolation level and concurrency control of MySQL transactions

As database application scenarios become increasingly complex, the isolation level and concurrency control of transactions have become a key issue in database management an indispensable and important topic. As a widely used relational database management system, MySQL's transaction processing functions are also highly valued by developers. This article will deeply explore the isolation level and concurrency control of MySQL transactions, and analyze it with specific code examples.

1. MySQL transaction isolation level

MySQL supports four transaction isolation levels, namely READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ and SERIALIZABLE. Different isolation levels have different effects on transaction concurrency control. Developers need to choose the appropriate isolation level based on actual needs.

1.1 READ UNCOMMITTED (read uncommitted)

READ UNCOMMITTED is the lowest isolation level, and transactions can read modifications made by other uncommitted transactions. Under this isolation level, there is the risk of dirty read (Dirty Read), that is, one transaction reads the data of another uncommitted transaction, which may cause data inconsistency.

-- 设置事务隔离级别为READ UNCOMMITTED
SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;

1.2 READ COMMITTED (read commit)

Under the READ COMMITTED isolation level, transactions can only read modifications made by other submitted transactions. This isolation level can avoid dirty reads, but there are still problems with non-repeatable reads and phantom reads.

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

1.3 REPEATABLE READ (repeatable read)

Under the REPEATABLE READ isolation level, the query results of a transaction will always remain consistent regardless of how other transactions modify the data during execution. This isolation level can avoid dirty reads and non-repeatable reads, but phantom reads may still occur.

-- 设置事务隔离级别为REPEATABLE READ
SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;

1.4 SERIALIZABLE (Serialization)

SERIALIZABLE is the highest level of isolation level. Transactions will be executed in order and transactions are guaranteed not to affect each other. This isolation level can avoid dirty reads, non-repeatable reads, and phantom reads, but will reduce concurrency performance.

-- 设置事务隔离级别为SERIALIZABLE
SET SESSION TRANSACTION ISOLATION LEVEL SERIALIZABLE;

2. Concurrency control of MySQL transactions

In MySQL, in order to ensure that concurrent execution between transactions will not cause data inconsistency problems, concurrency control is required. Commonly used concurrency control methods include locking, MVCC (Multi-version Concurrency Control), etc.

2.1 Locking

MySQL supports different granularity locking mechanisms such as row-level locks and table-level locks. Developers can choose the appropriate locking method according to the actual situation. The following is an example of using row-level locks:

-- 开启事务
START TRANSACTION;

-- 使用行级锁
SELECT * FROM table_name WHERE id = 1 FOR UPDATE;

-- 执行更新操作
UPDATE table_name SET column_name = 'new_value' WHERE id = 1;

-- 提交事务
COMMIT;

2.2 MVCC

MVCC is a commonly used concurrency control method in MySQL, which achieves concurrent access by saving different versions of data. When reading data, it will not be affected by the modified version of the writing transaction, ensuring the consistency of the read operation. The following is an example of MVCC:

-- 开启事务
START TRANSACTION;

-- 执行查询操作
SELECT * FROM table_name WHERE id = 1;

-- 提交事务
COMMIT;

Conclusion

The isolation level and concurrency control of MySQL transactions are important aspects that cannot be ignored in database management. Correctly configuring the isolation level and concurrency control methods can improve Database stability and performance. Through the introduction and examples of this article, I believe that readers will have a deeper understanding of the isolation level and concurrency control of MySQL transactions, and can better apply it in actual projects.

The above is an introduction to the isolation level and concurrency control of MySQL transactions. I hope it will be helpful to readers.

The above is the detailed content of MySQL transaction isolation level and concurrency control. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
How do you handle database upgrades in MySQL?How do you handle database upgrades in MySQL?Apr 30, 2025 am 12:28 AM

The steps for upgrading MySQL database include: 1. Backup the database, 2. Stop the current MySQL service, 3. Install the new version of MySQL, 4. Start the new version of MySQL service, 5. Recover the database. Compatibility issues are required during the upgrade process, and advanced tools such as PerconaToolkit can be used for testing and optimization.

What are the different backup strategies you can use for MySQL?What are the different backup strategies you can use for MySQL?Apr 30, 2025 am 12:28 AM

MySQL backup policies include logical backup, physical backup, incremental backup, replication-based backup, and cloud backup. 1. Logical backup uses mysqldump to export database structure and data, which is suitable for small databases and version migrations. 2. Physical backups are fast and comprehensive by copying data files, but require database consistency. 3. Incremental backup uses binary logging to record changes, which is suitable for large databases. 4. Replication-based backup reduces the impact on the production system by backing up from the server. 5. Cloud backups such as AmazonRDS provide automation solutions, but costs and control need to be considered. When selecting a policy, database size, downtime tolerance, recovery time, and recovery point goals should be considered.

What is MySQL clustering?What is MySQL clustering?Apr 30, 2025 am 12:28 AM

MySQLclusteringenhancesdatabaserobustnessandscalabilitybydistributingdataacrossmultiplenodes.ItusestheNDBenginefordatareplicationandfaulttolerance,ensuringhighavailability.Setupinvolvesconfiguringmanagement,data,andSQLnodes,withcarefulmonitoringandpe

How do you optimize database schema design for performance in MySQL?How do you optimize database schema design for performance in MySQL?Apr 30, 2025 am 12:27 AM

Optimizing database schema design in MySQL can improve performance through the following steps: 1. Index optimization: Create indexes on common query columns, balancing the overhead of query and inserting updates. 2. Table structure optimization: Reduce data redundancy through normalization or anti-normalization and improve access efficiency. 3. Data type selection: Use appropriate data types, such as INT instead of VARCHAR, to reduce storage space. 4. Partitioning and sub-table: For large data volumes, use partitioning and sub-table to disperse data to improve query and maintenance efficiency.

How can you optimize MySQL performance?How can you optimize MySQL performance?Apr 30, 2025 am 12:26 AM

TooptimizeMySQLperformance,followthesesteps:1)Implementproperindexingtospeedupqueries,2)UseEXPLAINtoanalyzeandoptimizequeryperformance,3)Adjustserverconfigurationsettingslikeinnodb_buffer_pool_sizeandmax_connections,4)Usepartitioningforlargetablestoi

How to use MySQL functions for data processing and calculationHow to use MySQL functions for data processing and calculationApr 29, 2025 pm 04:21 PM

MySQL functions can be used for data processing and calculation. 1. Basic usage includes string processing, date calculation and mathematical operations. 2. Advanced usage involves combining multiple functions to implement complex operations. 3. Performance optimization requires avoiding the use of functions in the WHERE clause and using GROUPBY and temporary tables.

An efficient way to batch insert data in MySQLAn efficient way to batch insert data in MySQLApr 29, 2025 pm 04:18 PM

Efficient methods for batch inserting data in MySQL include: 1. Using INSERTINTO...VALUES syntax, 2. Using LOADDATAINFILE command, 3. Using transaction processing, 4. Adjust batch size, 5. Disable indexing, 6. Using INSERTIGNORE or INSERT...ONDUPLICATEKEYUPDATE, these methods can significantly improve database operation efficiency.

Steps to add and delete fields to MySQL tablesSteps to add and delete fields to MySQL tablesApr 29, 2025 pm 04:15 PM

In MySQL, add fields using ALTERTABLEtable_nameADDCOLUMNnew_columnVARCHAR(255)AFTERexisting_column, delete fields using ALTERTABLEtable_nameDROPCOLUMNcolumn_to_drop. When adding fields, you need to specify a location to optimize query performance and data structure; before deleting fields, you need to confirm that the operation is irreversible; modifying table structure using online DDL, backup data, test environment, and low-load time periods is performance optimization and best practice.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools