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MySQL's ACID compliance

Mysql acid compliance

ACID is an acronym that stands for four key properties of database transactions:

Atomicity

Ensures that a transaction is treated as a single, indivisible unit of work

Either all operations within a transaction are completed successfully, or none are

If any part of the transaction fails, the entire transaction is rolled back to its previous state

Prevents partial updates that could leave the database in an inconsistent state

Consistency

Guarantees that a transaction brings the database from one valid state to another valid state

All data written to the database must adhere to defined rules, constraints, cascades, triggers, and other database integrity mechanisms

Ensures that any transaction will not break the database's predefined rules

Isolation

Determines how and when changes made by one transaction become visible to other transactions

Prevents interference between concurrent transactions

MySQL provides different isolation levels:

Read Uncommitted

Read Committed

Repeatable Read (default in InnoDB)

Serializable

Durability

Ensures that once a transaction is committed, it will remain committed even in the case of system failure

Committed data is saved to non-volatile storage

In MySQL, this is primarily managed by the InnoDB storage engine through write-ahead logging

MySQL ACID Compliance Details:


MySQL's InnoDB storage engine is fully ACID-compliant

MyISAM storage engine is not fully ACID-compliant and lacks some transaction features

When using InnoDB, MySQL provides robust transaction support that meets ACID requirements

Implementation Example:

START TRANSACTION;

UPDATE accounts SET balance = balance - 100 WHERE account_id = 1;

UPDATE accounts SET balance = balance + 100 WHERE account_id = 2;

COMMIT;

This transaction ensures that money is either fully transferred between accounts or not transferred at all, demonstrating ACID principles.

Key Considerations:

Always use InnoDB for transactions requiring full ACID compliance

Configure appropriate isolation levels based on your specific use case

Use transactions for operations that require multiple related database modifications

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