You do not use the Premiere Products database for any of these exercises.
1. While users were updating the Premiere Products database, one of the transactions was interrupted. You need to explain to management what steps the DBMS will take to correct the database. Using the sample log, list and describe the updates that the DBMS will roll back if transaction 2 is interrupted at 8:10.
2. Occasionally, users at Premiere Products obtain incorrect results when they run queries that include built-in (aggregate, summary, or statistical) functions. The DBA told management that unrepeatable reads caused the problems. Use books, articles, and/or the Internet to research the unrepeatable read problem. Write a short report that explains the unrepeatable-read problem to management and use an example with your explanation. (Note: Unrepeatable reads are also called inconsistent retrievals, dirty reads, and inconsistent reads.)
3. You’ve explained replication to management, and some managers ask you for examples of when replication could be useful to them. Describe two situations, other than the ones given in the text, when replication would be useful to an organization.
This material may consist of step-by-step explanations on how to solve a problem or examples of proper writing, including the use of citations, references, bibliographies, and formatting. This material is made available for the sole purpose of studying and learning - misuse is strictly forbidden.1. Answer:
a. Because the database has not actually been destroyed, the problem involved transaction that were stopped in midstream so we use backward recovery
b. We will read the log for problem and apply the before image to undo our updates
c. We know that transaction 2 is interrupted at 8:10
d. The DBMS started transaction 2 at 8:01, added an Order table record at 8:02, an OrderLine record at 8:05 and 8:09. Because no before image exits for adding a record, to roll back transaction 2 , the DBMS deletes the Order and OrderLine table record....
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