Before a block of data in main memory can be output to the database, all log records pertaining to data in that block must have been output to stable storage. This is
A. Read-write logging
B. Read-ahead logging
C. Write-ahead logging
D. None of the mentioned
Answer:A
Before a block of data in main memory can be output to the database, all log records pertaining to data in that block must have been output to stable storage. This is
A. Read-write logging B. Read-ahead logging C. Write-ahead logging D. None of the mentioned
Explanation: The WAL rule requires only that the undo information in the log has been output to stable storage, and it permits the redo information to be written later.