Chapter 19, Problem 24E

Explanation of Solution

Comparison of log-based recovery with the shadow-copy scheme in terms of their overheads:

• In log-based recovery, a log is created in stable storage for each transaction.
• Whereas in shadow-copy scheme, a transaction is performed on the local copy of the database.
• With log-based recovery, each update in database is written twice as follows:
  • Once as a part of the page to which it is written.
  • Once as a part of the log record for the update.
• While shadow copying does not involve in log writes. But here, I/O operations are increased and concurrency decreases when it comes to the data that is added for the first time to a newly allocated disk page...