How do transactions work in relational databases and what is ACID?

Question

Accepted Answer

A transaction is a logical unit of work that combines multiple database operations into a single indivisible process. If even a single operation fails, the entire transaction is rolled back, returning the database to its initial state. This is critically important for maintaining data integrity, for example, when transferring money from one bank account to another.

The ACID acronym describes four key properties of reliable transactions. Atomicity guarantees that all changes are executed completely or not at all. Consistency ensures that a transaction transitions the database from one valid state to another while adhering to all constraints and integrity rules.

Isolation defines how independently concurrent transactions are executed from one another. Finally, durability means that after a transaction is successfully committed, the changes will not be lost even in the event of a system failure. To manage database isolation, isolation levels are used, which help balance between performance and data accuracy.

When working with transactions, it is important for a developer to follow several rules to avoid performance and locking issues:

1. Try to make transactions as short as possible in execution time.
2. Do not perform long network requests or computations inside an open transaction.
3. Define the isolation level corresponding to the application's business logic in advance.
4. Always handle errors and write explicit rollbacks of changes upon failures.

How do transactions work in relational databases and what is ACID?

More questions in this topic

Related questions from other topics