Understanding Database Transactions, ACID Principles, and Spring @Transactional Behavior

The article explains why data safety and accuracy are crucial for developers and introduces the concept of database transactions along with the ACID properties (Atomicity, Consistency, Isolation, Durability).

It describes how InnoDB implements ACID using undo logs, redo logs, and locks, and how Spring’s @Transactional annotation relies on AOP dynamic proxies to start, commit, or roll back a transaction.

Key points include that by default only RuntimeException triggers a rollback, how to use @Transactional(rollbackFor = Exception.class) to roll back checked exceptions, and common scenarios where transactions fail: private methods, self‑invocation, multi‑threaded execution, and improper try‑catch handling.

Several code examples illustrate the annotation usage, exception handling, and the effect of different configurations on database state, accompanied by screenshots of test results.

The article concludes with a summary of best practices: ensure transactional methods are public, use AOP‑compatible proxies, specify rollback rules when needed, and be aware of thread boundaries and exception types.