Write-ahead logging and the ARIES crash recovery algorithm

How do databases recover from failure?

A central tenet of databases is that any committed data survives a crash or a failure. Write-ahead logging is a fundamental primitive that ensures all changes to data are first written safely to stable storage before being applied. Coupling that with some careful use of sequence numbers and we can guarantee that changes made to a database can survive system crashes. Motivation Let’s start with a simple transaction T1 that reads object A, and updates the value for A with a write. [Read More]