databastransaktioner

A databastransaktion, often referred to as a database transaction, is a sequence of operations performed as a single logical unit of work. These operations are performed on a database. The fundamental principle behind transactions is to ensure data integrity and consistency, even in the event of system failures or concurrent access. Transactions are governed by a set of properties known as ACID: Atomicity, Consistency, Isolation, and Durability.

Atomicity means that a transaction is treated as a single, indivisible unit. Either all of its operations are successfully completed, or none of them are. If any part of the transaction fails, the entire transaction is rolled back, and the database is left in its original state, as if the transaction never occurred.

Consistency ensures that a transaction brings the database from one valid state to another. It guarantees that any data written to the database must be valid according to all defined rules, including constraints, cascades, and triggers.

Isolation means that concurrent transactions are isolated from each other. The effects of an incomplete transaction should not be visible to other transactions. This prevents issues like dirty reads, non-repeatable reads, and phantom reads, ensuring that each transaction operates on a consistent snapshot of the data.

Durability guarantees that once a transaction has been committed, its changes are permanent and will survive even a system failure, such as a power outage or crash. Committed data is typically written to non-volatile storage.

Database transactions are crucial for reliable data management in applications ranging from banking systems to e-commerce platforms, ensuring that data remains accurate and dependable.