[Announcements | Schedule and Readings | Assignments and Quizzes | Syllabus/Policies ]

Reading Questions, Lecture 15 (10/27)

Papers: Transaction Management in R*, Dangers of Replication and A Solution

These papers talk about distributed transactions and replication -- though the second paper doesn't talk about ACID-style transactions as we have discussed them it is related in that there are new consistency requirements that replication introduces.

As you read the papers, consider the following questions:

  1. In the "R*" paper, how does the two phase commit (2PC) protocol work? What problem does it solve? What are the costs of using it?
  2. What is the significance of the Presumed Abort/Presumed Commit variants of 2PC? How do they reduce the overhead of 2PC? When should you choose one over the other?
  3. In the "Dangers of Replication" paper, what are the tradeoffs between lazy/eager and group/master replication in terms of read performance, write performance, and availability?
  4. What is the "danger of replication" to which this paper refers?
  5. What is the "solution"? Do you buy that this is a reasonable way to solve this problem?

Samuel Madden (madden at csail dot mit dot edu)
Last modified: Sat Nov 6 18:08:47 EST 2004