Data Base Management System | Week 5
Course Name: Data Base Management System
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These are Data Base Management System Week 5 Assignment Answers
Q1. Which of the following can be the solution(s) for Password Leakage Problem in Database Servers?
a) Two-factor authentication (password plus one-time password sent by SMS).
b) Storing encrypted passwords in database and in scripts.
c) Using the same password across different sites.
d) Single-factor authentication using usernames and passwords.
Answer: a, b
These are Data Base Management System Week 5 Assignment Answers
Q2. In a file structure of Variable-Length Records, which of the following does a slotted page header contain?
a) block pointer
b) number of record entries
c) end of free space in the block
d) size of the next record
Answer: b, c
These are Data Base Management System Week 5 Assignment Answers
Q3. A file organization is sequential and unspanned (one block can store only whole records). The disk block size is 512 bytes. Each record of the file is 32 bytes long and the block pointer size is 12 bytes. How many records can be stored in one block?
a) 17
b) 16
c) 15
d) 14
Answer: c) 15
These are Data Base Management System Week 5 Assignment Answers
Q4. Suppose that the record of a book in a library is 300 bytes long. The details of the disk storage is as follows. The disk unit rotates at 7200 rpm (revolutions per minute). The data transfer rate of the disk is 75000 bytes per second whereas seek time is 20 milliseconds. One block contains 5 such records of the book. If a student asks to know the details of a given book, how much time will be required to know that?
a) Approx. 441 milliseconds
b) Approx. 44 milliseconds
c) Approx. 24 milliseconds.
d) Approx. 4 milliseconds
Answer: b) Approx. 44 milliseconds
These are Data Base Management System Week 5 Assignment Answers
Q5. What is the availability of a Database Management System having the following reliability parameters? Mean Time Between Failure (MTBF) = 36 days Mean Time to Repair (MTTR) = 18 hours
a) 20.01%
b) 64.25%
c) 97.95%
d) 99.02%
Answer: c) 97.95%
Q6. Suppose that a disk drive has 200 tracks, numbered 0 to 199. The queue of pending requests
in FIFO order is: 75, 142, 93, 177, 48, 150, 102, 171, 136.
The read-write head initially is on track 45. What is the total distance that the disk head will move to satisfy all pending requests following first cum first serve(FCFS) scheduling algo-rithms?
a) 563
b) 613
c) 633
d) 823
Answer: b) 613
These are Data Base Management System Week 5 Assignment Answers
Q7. Suppose that a Database Management System uses the Most Recently Used (MRU) strategy as its buffer replacement policy. Further, suppose that the system allocates 4 free buffer blocks for execution of a query to be used as a buffer. Assume that a query requires to access the following disk blocks in that order to complete its execution:
9,5,1,2,5,3,5,4,2,3,5,3,2,1,2,5,1,9,5,1
Calculate the number of block replacements (when all blocks are full, a residing block is replaced with a required block) required to complete the query.
a) 7
b) 8
c) 9
d) 10
Answer: a) 7
These are Data Base Management System Week 5 Assignment Answers
Q8. Consider the following statements:
1: Copy the required block from the disk to the main memory buffer.
2: The program calls the buffer manager for the required block.
3: Buffer manager returns the address of the block residing in main memory to the pro-gram.
4: Replace some other block, if the buffer blocks in main memory are not free.
There are a few statements written above. Arrange them in order to resolve what happens, when a program identifies that a required block is not available in the main memory buffer.
a) 2,3,1,4
b) 2,3,4,1
c) 24,31
d) 2,4,1,3
Answer: d) 2,4,1,3
These are Data Base Management System Week 5 Assignment Answers
Q9. Consider the following schema:
Member (Mid, Fname, Lname, Domain, Gender, Mobile_no, DOI)
Journal publication(DOI, J name, J_type, No_of publication, Mid) with the following functional dependencies:
Mid — Fname, Lname, Domain, Cender, Mobile_no
Mid — DOI
DOI — Mid
DOI—+ Jname, J_type, Noof publication
‘Which will be the refined optimal schema from the followings?
a) Member(Mid, Fname, Lname, Domain, Gender, Mobile.no, DOI)
Journal _publication(DOI, J.name, J_type, No_of publication, Mid)
Jounal 1ist(DOI, Mid)
b) Member(Mid, Fname, Lname, Domain, Gender, Mobile no)
Journal publication(DOI, J.name, J_type, No_of publication, Mid)
c) Member (Mid, Fname, Lname, Domain, Gender, Mobile no, DOI)
Journal publication(DOI, J.name, J_type, No_of publication)
Jounal 1list(DOI, Mid)
d) Member(Mid, Fname, Lname, Domain, Gender, Mobile no)
Journal publication(DOI, J.name, J_type, No_of publication)
Answer: d) Member(Mid, Fname, Lname, Domain, Gender, Mobile no)
Journal publication(DOI, J.name, J_type, No_of publication)
These are Data Base Management System Week 5 Assignment Answers
Q10. Suppose you have a 128-gigabyte flash storage system with a 2048-byte page size. How big would the flash translation table be, assuming each page has a 32-bit address, and the table is stored as an array?
a) 256 megabytes
b) 32 megabytes
c) 64 bytes
d) 32 bytes
Answer: b) 32 megabytes
These are Data Base Management System Week 5 Assignment Answers
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These are Data Base Management System Week 5 Assignment Answers
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