Quiz 9 - Transaction Management and Concurrency Control

12/14/24, 2:01 AM Quiz: Transaction Management and Concurrency Control: COMP 440 DATABASE DESIGN - (17042-FA2024) Quiz: Transaction Management and Concurrency Control Due Dec 6 at 11:59pm Points 15 Questions 15 Time Limit 30 Minutes Allowed Attempts 2 Take the Quiz Again Attempt History LATEST Attempt Time Score Attempt 1 23 minutes 13 out of 15 * * Some questions not yet graded  Correct answers are hidden. Score for this attempt: 13 out of 15 * * Some questions not yet graded Submitted Dec 6 at 10:56pm This attempt took 23 minutes.  Question 1 1 / 1 pts The database for the pet store where you work has one transaction that is not committed, and a second transaction is executed. This is called: overwritten data lost update Correct. The update from transaction one to two is lost. https://canvas.csun.edu/courses/154575/quizzes/571412 1/7 12/14/24, 2:01 AM Quiz: Transaction Management and Concurrency Control: COMP 440 DATABASE DESIGN - (17042-FA2024) lost data data update  Question 2 1 / 1 pts _____ ensure that a disk physical failure will not impair the DBMS's ability to recover data. transaction logs buffers redundant transaction logs Correct. Redundant transaction logs are multiple copies of the transaction log kept by the DBMS to ensure that the physical failure of a disk will not impair recovery of data. checkpoints  Question 3 1 / 1 pts The _____ protocol ensures that transaction logs are always written before any database data is actually updated. write-ahead-log Correct. Write-ahead-log ensures that transaction logs are written to permanent storage before the database data is actually updated. redundant transaction log transaction log deferred-write-log  Question 4 1 / 1 pts When you design a multi-user database the open use of a data items to multiple transactions is guaranteed by a ________________ in the DBMS. exclusive lock https://canvas.csun.edu/courses/154575/quizzes/571412 2/7 12/14/24, 2:01 AM Quiz: Transaction Management and Concurrency Control: COMP 440 DATABASE DESIGN - (17042-FA2024) lock Correct. A lock guarantees exclusive use of data to a concurrent transaction, not multiple transactions. shared lock deadlock  Question 5 1 / 1 pts In the wait/die scheme of concurrency control, the ______ younger, preempted transaction is rescheduled using the same time stamp. younger and older transactions both wait indefinitely to be released. older transaction rolls back the younger transaction and reschedules it. older transaction waits for the younger one to complete and release its locks. Correct. T1 waits until T2 completes then T2 releases its lock in the wait/die scheme.  Question 6 1 / 1 pts Database __________________ are an operation in which the database management system writes all of its updated buffers to disk, while this is happening DBMS does not execute any new requests. checkpoint Correct. Checkpoint is an operation in which the DBMS writes all of its updated buffers to disk. buffer logs redundant transaction logs  Question 7 1 / 1 pts https://canvas.csun.edu/courses/154575/quizzes/571412 3/7 12/14/24, 2:01 AM Quiz: Transaction Management and Concurrency Control: COMP 440 DATABASE DESIGN - (17042-FA2024) You decide to use the __________________ phase of the optimistic approach in the concurrency method to validate the transaction to ensure that the changes made will not affect the integrity and consistency of the database. validation phase Correct. Validation is when the transaction is validated to ensure the changes made will not affect the integrity and consistency of the database. write phase data phase read phase  Question 8 1 / 1 pts When designing a multi-user database, you want to use ANSI defined events that are equivalent to a ROLLBACK. Which of the following are the events that you would utilize? All changes are aborted and returned to a previous consistent state. Correct. ROLLBACK is all changes removed and returned to the previous consistent state. The end of a program is successfully reached. The database is shut down for maintenance. Five SQL statements are executed.  IncorrectQuestion 9 0 / 1 pts When creating a multi-user database, you will set a _________ on the entire table so that it is locked, preventing access to transaction 1 by transaction 2 while transaction 1 is accessing the table. page-level transaction-level row-level https://canvas.csun.edu/courses/154575/quizzes/571412 4/7 12/14/24, 2:01 AM Quiz: Transaction Management and Concurrency Control: COMP 440 DATABASE DESIGN - (17042-FA2024) table-level Incorrect. Page-level locks the entire page preventing Transaction 1 access while Transaction 2 is accessing.  Question 10 1 / 1 pts The DBMS guarantees that the semantic meaning of a transaction truly represents the real-world event. True False Correct. DBMS guarantees the meaning of the transaction which represents a single SQL statement not a real-world event.  Question 11 1 / 1 pts The database in the pet store where you work has two transactions that are being executed concurrently. The first transaction is rolled back after the second transaction has already accessed the uncommitted data. These transactions violated the _____________________ property of transactions. Isolation Correct. Isolation property is a data item from one transaction that is not available until the other transaction completes. Durability Rollback Serializability  Question 12 1 / 1 pts When designing the multi-user database for a grocery store you decide to use the ___________ approach to scheduling concurrent transactions that assigns a global unique stamp to each transaction. time stamping Correct. Time stamping assigns a global, unique time to each transaction. unique https://canvas.csun.edu/courses/154575/quizzes/571412 5/7 12/14/24, 2:01 AM Quiz: Transaction Management and Concurrency Control: COMP 440 DATABASE DESIGN - (17042-FA2024) scheduled table-locking  Question 13 1 / 1 pts Time stamps must only have the single property of uniqueness. True False Correct. Time stamps have two properties of uniqueness and monotonicity.  Question 14 1 / 1 pts You develop a single-user database system that only one transaction is executed at a time. These two isolation properties automatically ensure the integrity of the database. serializability and durability atomicity and serializability serializability and isolation Correct. Serializability and isolation are properties of a single-user database that automatically ensures only one transaction at a time is executed. atomicity and isolation  Question 15 Not yet graded / 1 pts What are database checkpoints? Your Answer: Database checkpoints are operations in which the DBMS writes all of its updated buffers in memory to disk. https://canvas.csun.edu/courses/154575/quizzes/571412 6/7 12/14/24, 2:01 AM Quiz: Transaction Management and Concurrency Control: COMP 440 DATABASE DESIGN - (17042-FA2024) Answer: See the 'Rationale' field for sample responses. Rationale: Database checkpoints are operations in which the DBMS writes all of its updated buffers to disk. While this is happening, the DBMS does not execute any other requests. A checkpoint operation is also registered in the transaction log. As a result of this operation, the physical database and the transaction log will be in sync. This synchronization is required because update operations update the copy of the data in the buffers and not in the physical database. Checkpoints are automatically scheduled by the DBMS several times per hour. Checkpoints also play an important role in transaction recovery. Quiz Score: 13 out of 15 * Some questions not yet graded https://canvas.csun.edu/courses/154575/quizzes/571412 7/7