Understanding ACID in MySQL

ACID is a set of four essential properties in database management that ensure data integrity and consistency, even in catastrophic failures. This guide provides a concise overview of how ACID works in MySQL, with examples to illustrate each property.

Atomicity

Ensures that all statements in a transaction are executed as a single unit. If one part fails, the entire transaction fails.

START TRANSACTION;
INSERT INTO accounts (id, balance) VALUES (1, 100);
INSERT INTO accounts (id, balance) VALUES (2, 200);
COMMIT;

Consistency

Maintains database consistency before and after the transaction by adhering to predefined rules.

START TRANSACTION;
UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;
COMMIT;

Isolation

Ensures that transactions are executed in isolation from one another.

SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
START TRANSACTION;
SELECT * FROM accounts WHERE id = 1;

Durability

Guarantees that once a transaction is committed, it will remain so even in the event of a system crash.

START TRANSACTION;
INSERT INTO transactions (id, amount) VALUES (1, 100);
COMMIT;

FAQ

What is ACID?

ACID stands for Atomicity, Consistency, Isolation, and Durability, crucial for ensuring data integrity in databases.

Why is ACID important in MySQL?

ACID properties ensure reliable transactions, preventing data corruption and maintaining consistency even in failures.

Can ACID be modified for performance?

Yes, parameters in MySQL’s configuration file (my.cnf or my.ini) can be adjusted for speed, balancing between performance and ACID compliance.

What storage engines support ACID in MySQL?

InnoDB and Percona’s XtraDB are the primary storage engines supporting ACID in MySQL.

Conclusion

Understanding ACID properties is fundamental for managing MySQL databases effectively. These principles ensure data reliability and integrity. For an in-depth guide, check out A Guide to ACID In MySQL.