choice.txt

ssd7考试exam3,绝对有用~欢迎下载

	1. 	
	Which of the following is true about the growing phase and the shrinking phase of a strict two-phase locking protocol? 	

	(a) The growing phase ends shortly after the start of the transaction when all locks for the transaction must be acquired.
(b) The growing phase ends just before commit.
(c) There is a plateau phase when locks are neither released nor acquired; this phase comes between the growing phase and the shrinking phase.
(d) The growing phase must be in the first half of the transaction and the shrinking phase must be in the second half.

	Correct answer is 	(b)

	Your score on this question is: 	5.00 	

	2. 	
	Which of the following will a good hash function do? 	

	(a) concentrate keys in one location
(b) spread keys around the file as evenly as possible
(c) spread keys around the file in heaps
(d) leave gaps in the file at periodic intervals for future growth

	Correct answer is 	(b)

	Your score on this question is: 	5.00 	

	3. 	
	An index file is usually used to index ______ of the data file. 	

	(a) two fields
(b) one field
(c) all fields
(d) most fields

	Correct answer is 	(b)

	Your score on this question is: 	5.00 	

	4. 	
	A collision occurs in hashing when the bucket in which the record to be _____ 	

	(a) stored is full
(b) deleted has exactly one record
(c) deleted is full
(d) stored has at least one other record

	Correct answer is 	(a)

	Your score on this question is: 	5.00 	

	5. 	
	The undo action undoes the effects of a(n) _____ transaction, and the redo action redoes the effects of a(n) _____ transaction. 	

	(a) committed, aborted
(b) aborted, committed
(c) aborted, aborted
(d) committed, committed

	Correct answer is 	(b)

	Your score on this question is: 	5.00 	

	6. 	
	Which of the following is true about compensating transactions? 	

	(a) The DBMS cannot automatically write compensating transactions.
(b) The DBMS can automatically write compensating transactions.
(c) The DBMS will automatically write a compensating transaction for each committed transaction.
(d) The user can request the DBMS to write compensating transactions automatically.

	Correct answer is 	(a)

	Your score on this question is: 	5.00 	

	7. 	
	A cluster index is an index defined on a(n) _____ field. 	

	(a) non-ordering
(b) alternate key
(c) ordering
(d) primary key

	Correct answer is 	(c)

	Your score on this question is: 	5.00 	

	8. 	
	Which concurrency control protocols perform best in all situations? 	

	(a) pessimistic protocols
(b) none
(c) two-phase locking protocols
(d) optimistic protocols

	Correct answer is 	(b)

	Your score on this question is: 	5.00 	

	9. 	
	A shared lock on a data item represents permission to perform which of the operations, read and write, on the data item? 	

	(a) Neither read nor write
(b) Both read and write
(c) Write only
(d) Read only

	Correct answer is 	(d)

	Your score on this question is: 	0.00 	

	10. 	
	How does linear probing solve the problem of collisions in hashing? 	

	(a) The hash file is probed linearly from the end to find the first available slot.
(b) A serial search is performed from the point of collision to find the first available slot.
(c) The hash file is probed linearly from the start to find the first available slot.
(d) A linear function is used to determine the next spot to search for slots.

	Correct answer is 	(b)

	Your score on this question is: 	5.00 	

	11. 	
	In a network database, the first record of an ordered linked list that represents a one-to-many relationship is called a(n) 	

	(a) intermediary
(b) owner
(c) link
(d) vector

	Correct answer is 	(b)

	Your score on this question is: 	5.00

	Feedback: 	
   

See section 5.1.3, subsection "Network Data Model," in the course notes.
	

	12. 	
	In a hierarchical database, data records are represented using which of the following data structures? 	

	(a) Matrices
(b) Hash tables
(c) Arrays
(d) Trees

	Correct answer is 	(d)

	Your score on this question is: 	5.00

	Feedback: 	
   

See section 5.1.3, subsection "Hierarchical Data Model," in the course notes.
	

	13. 	
	Which of the following collections allows duplicate elements?

   1. set
   2. multiset
   3. list

	

	(a) III only
(b) I, II, and III
(c) II only
(d) II and III only

	Correct answer is 	(d)

	Your score on this question is: 	5.00 	

	14. 	
	

In a hierarchical database, a single tree can accommodate which of the following types of binary relationships?

   1. One-to-one relationships
   2. One-to-many relationships
   3. Many-to-many relationships

	

	(a) I, II, and III
(b) I only
(c) I and II only
(d) None

	Correct answer is 	(c)

	Your score on this question is: 	5.00

	Feedback: 	
   

See section 5.1.3, subsection "Hierarchical Data Model," in the course notes.
	

	15. 	
	To retrieve data from a hierarchical database, program logic for performing _____ must be available. 	

	(a) relational joins
(b) decomposition
(c) navigation
(d) polymorphism

	Correct answer is 	(c)

	Your score on this question is: 	5.00

	Feedback: 	
   

See section 5.1.3, subsection "Hierarchical Data Model," in the course notes.
	

	16. 	
	In a network database, data records are represented using which of the following data structures? 	

	(a) Arrays
(b) Hash tables
(c) Graphs
(d) Matrices

	Correct answer is 	(c)

	Your score on this question is: 	5.00

	Feedback: 	
   

See section 5.1.3, subsection "Network Data Model," in the course notes.
	

	17. 	
	In a network database, a binary one-to-many relationship is typically represented using a 	

	(a) sparse matrix
(b) binary tree
(c) hash table
(d) linked list

	Correct answer is 	(d)

	Your score on this question is: 	5.00

	Feedback: 	
   

See section 5.1.3, subsection "Network Data Model," in the course notes.
	

	18. 	
	Which of the following types of databases store data in tables and represent relationships using foreign keys? 	

	(a) Object-oriented databases
(b) Hierarchical databases
(c) Network databases
(d) Relational databases

	Correct answer is 	(d)

	Your score on this question is: 	5.00

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See section 5.1.3, subsection "Relational Data Model," in the course notes.
	

	19. 	
	Small, highly focused databases at the departmental level that are used to build enterprise-wide data warehouses are known as 	

	(a) data marts
(b) data cubes
(c) hypercubes
(d) virtual data warehouses

	Correct answer is 	(a)

	Your score on this question is: 	5.00

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5.2#Issues and Categories of Data Warehouses
	

	20. 	
	

Which of the following statements is (are) typically true of hierarchical databases?

   1. They are navigated using preorder traversals.
   2. Their users must be aware of the databases’ internal tree structures.

	

	(a) None
(b) II only
(c) I only
(d) I and II

	Correct answer is 	(d)

	Your score on this question is: 	5.00

	Feedback: 	
   

See section 5.1.3, subsectio