Write-Ahead Logging (WAL)

Problem

The server rack just lost power immediately after a user committed a transaction. Miraculously, when the database reboots, the data is still there, even though the main data file hadn't been updated yet. This is due to the transaction log. Write a query that outputs purpose with the value: "WAL ensures database durability by logging changes to disk before applying them to the actual data files."

Database Schema

This problem acts as a scratchpad. You will write your own DDL/DML or conceptual queries, so there is no predefined schema.

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Hint

Solution