ACID characteristics and implementation methods of MySQL relational database transactions

This article mainly introduces "MySQLRelational DatabaseACID characteristics and implementation methods of transactions", in daily operations, I believe many people have doubts about the ACID characteristics and implementation methods of MySQL relational database transactions.I hope it will be helpful for you to answer your doubts about "ACID characteristics and implementation methods of MySQL relational database transactions"!Next, please follow the editor to learn together!

1. ACID characteristics of transactions in detail

ACID are four properties that must be present in order to ensure that a transaction is correct and reliable:

• Atomicity: Operations in a transaction succeed or fail simultaneously.

• Consistency: Database transactions cannot destroy data integrity and business logic consistency.

• Isolation: A transaction does not affect the operation of other transactions.

• Durability: After the transaction is completed, the changes made by the transaction should be persisted in the database and will not be rolled back.

Take A transfer 100 yuan to B as an example:

• Atomicity: A loses $100 at the same time as B receives $100.

• Consistency: A's account cannot be negative after losing 100 yuan.

• Isolation: If account A loses 1 yuan when executing B transaction while executing the transaction, it will eventually lose 101 yuan, and the two do not affect each other.

• Persistence: After A's account loses 100 yuan, it cannot be recovered.

2. Implementation of MySQL transaction

MySQL transactions are implemented by the InnoDB storage engine.

A transaction can be started explicitly with the following command:

start transaction / (Begin);#One or more sql statements Commit;

In addition, in autocommit mode, each SQL statement we execute is a separate transaction; if autocommit mode is turned off, all SQL statements are in a transaction untilA commit or rollback is performed, the transaction ends, and another transaction begins.

The ACID properties of MySQL transactions are achieved by the following mechanisms:

• Atomicity: undo log, logical log, records information related to SQL execution.When a rollback occurs, InnoDB will do the opposite according to the contents of the undo log

• Persistence: redo log, when the transaction is committed, the fsync interface will be called to flush the redo log.

• Isolation: Locking mechanism and MVCC.

• Consistency: The design of the database itself.

3. Use of Gorm Transactions

Go's Gorm provides support for transactional operations:

db.Transaction(func(tx *gorm.DB) error { // Do some db operations in a transaction (from here you should use 'tx' instead of 'db') if err := tx.Create(&Animal{Name: "Giraffe"}).Error; err != nil { // Returning any error will rollback the transaction return err } if err := tx.Create(&Animal{Name:"Lion"}).Error; err != nil {   return err } } // return nil Commit transaction return nil})

In addition, there are operations such as nested transactions and manual transactions, you can refer to the Chinese document: Go GORM Transaction Details

4. Use of Spring Transactions

public class AClass {   @Transactional(rollbackFor = Exception.class) public void aFunction() {       //todo: database operation A (add, delete, this)   }}

The @Transactional annotation must be added to public methods. Private and protected methods are invalid.

In general, it is recommended to add the @Transactional annotation to the method, because @Transactional is directly added to the class or interface, and the @Transactional annotation will be valid for all public methods in the class or interface, which will affect performance.

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