MySQL WAL stands for Write-Ahead Logging. It is a technique used to ensure the durability of database transactions.
When a transaction is executed in MySQL, it is first written to a transaction log file before being applied to the actual database. This allows for quick recovery and rollback in the event of a system failure or crash.
The transaction log file records all changes made to the database in a sequential order, with each entry containing the data being modified, as well as information regarding when and by whom the update was made.
By using WAL, MySQL can ensure that all transactions are atomic and durable in the event of a power outage, system crash, or other unexpected errors. This enhances the reliability and consistency of the database system.