CS422 HW5

Homework 5
CS422, Spring 2012

Due: Thursday, May 31

Please upload your files to CSNS. Note that file uploading will be disabled automatically after 11:59PM of the due date, so please turn in your work on time.

1. (30pt) For a transaction T, consider the following sequence of operations performed by a DBMS:

Start Transaction
<START, T>
<UPDATE, T, X, v_x, v_x'>
Write(X, v_x')
<UPDATE, T, Y, v_y, v_y'>
Write(Y, v_y’)
Flush(log);
Flush(X);
<COMMIT, T>
Flush(log)
Commit;
Flush(Y)

Suppose a system crash may happen between any two operations in the sequence. Please answer the following questions:

(a) Can the DBMS recover from a system crash using Undo-only Recovery? If the answer is no, use an example to explain why.

(b) Can the DBMS recover from a system crash using Redo-only Recovery? If the answer is no, use an example to explain why.

(c) Can the DBMS recover from a system crash using Undo/Redo Recovery? If the answer is no, use an example to explain why.

For this exercise, please put your answers in a file in TXT, PDF, DOC, or ODT format and upload it to CSNS.

2. (60pt) Implement Undo/Redo Recovery in SimpleDB, including test code to show that your implementation works correctly. For this exercise, you must submit two files:

A zip file of the src folder of the SimpleDB project.
A document that describes your implementation and how to test it. This document should include a list of files that you added/modified, and a brief description of the functionality you implemented in each file. The document should also include instructions for testing your code and verifying the results.

To receive full credit for this exercise, your imiplementation may only keep one block of the log records in memory at any time.