Glossary term
What is WAL (Write-Ahead Log)?
WAL stands for Write-Ahead Log.
Changes are written to a log before the data files. Example: Makes crash recovery and replication possible.
Learn it properly · System DesignLesson 21: ACID Transactions & Isolation LevelsTwo people book the last seat; a transfer crashes halfway. What ACID really promises, the write-ahead log behind durability, the five anomalies isolation levels do (and don't) prevent, and the practical fixes for real race conditions.