Preparation for Recitation 17

Read Concurrency Control and Recovery, by Michael J. Franklin.

This paper is quite long, so you may want to digest the paper in a few chunks. The first two sections are a good review of the basics of locking and logging that will be discussed in lectures this week. Recitation will focus on Section 3, and in particular on the ARIES recovery algorithm.

After reading the paper, answer the following question:

What is the purpose of compensation log records (CLRs) during ARIES recovery? What could go wrong if they weren't used?