Eastern Mediterranean University
Department of Computer
Engineering
CMPE 352 - Midterm Exam
2001 – 2002 Summer School
16 August 2002
Name, Surname
Student No
Group No
:…………………..
:…………………..
:…………………..
Instructor:
Visit. Assoc. Prof. Alexander CHEFRANOV
Duration: 2 Hours
INSTRUCTIONS:
1. Please answer all questions.
2. Do not ask any question to the invigilator.
3. GSM phones should be turned off.
Questions
I
II-1
II-2
II-3
II-4
Total
GOOD LUCK!
1
Marks
PART 1: Storage and File Sructure, Query Processing and Optimization
(3 points each question)
1)
Number (in the boxes) the following memory types according to read access
time in ascending order:
4
5
3
2
1
2)
floppy dısks
magnetıc tapes
hard dısks
flash memory
cache memory
Cylinders of a magnetic disk were introduced because of:
a) the large disks capacity
b) placing magnetic heads on the common arm
c) placing magnetic platters on the common spindle
d) large rotational speed of the magnetic platters
e) none of the above
3)
Rotational latency is a time required to find
a) a disk
b) a head
c) a cylinder
d) a sector
e) none of the above
4)
RAID level 0 organization reduces
a) rotational speed
b) queries execution time
c) rotational latency
d) number of disk block accesses
e) none of the above
5)
MRU buffer management algorithm assumes to replace the page which
a) was most frequently used
b) was most randomly used
c) was not used for the most time
d) was used the last before the current moment
e) none of the above
2
6) To insert new tuple in the fixed-length records file with preservation of tuples
ordering according to some key there must be maintained
a) a list of attributes;
b) a linked list of existing tuples;
c) a linked list of deleted tuples;
d) a linked list of pointers
e) nothing of the above
7)
Hardware swizzling of persistent pointers assumes using of
a) volatile memory;
b) virtual memory;
c) tertiary memory;
d) cache memory
e) none of the above
8)
Assume that we have a clustering index on the A attribute of the r(A,B,C)
relation. Which of the following is necessarily correct?
a) A is a candidate key of r
b) A is a superkey key of r
c) t1(A) < t2(A) -> t1 precedes t2 in r,
where t1, t2 are tuples of r,t1(A), t1(A) are the values of field A in
the tuples, -> sign of implication
d) index must be sparse
e) none of the above
9)
Assume that we have a secondary index on the A attribute of the r(A,B,C)
relation. Which of the following is necessarily correct?
a) the index is clustering
b) the index is sparse
c) the index is ordered
d) the index is dense
e) none of the above
3
For questions 10 - 13, assume that r(A,B,C), s(C,D) are relations. Let the number of
tuples in r be 300, the number of tuples in s be 600. A block on disk can hold 30 records
of r and 25 records of s.
10)
What is the number of records in r |><| s (r natural join s) if C is a foreign key
in s for r?
a) 300
b) 600
c) 900
d) 1200
e) other value:
11)
What is a good estimate of the number of records in r |><| s (r natural join s)
if C is not a key of r and C is not a key of s? Assume that there are 10
distinct C values in r and 20 distinct C values in s.
a) 30 x 600
b) 20 x 600
c) 15 x 600
d) 10 x 60
e) other value:
12)
How many block accesses are needed to compute a natural join r |><| s, if r
is traversed in the outer loop of the block-nested loop join and memory
size M=10 (can accommodate 10 disk blocks)?
a) 10 + 10x24
b) 24+24x10
c) 10+2x24
d) 24 + 3x10
e) other value:
13)
How many block accesses are needed to compute the join r |><| s, if s is
traversed in the outer loop of the nested loop join and memory size M=15
(can accommodate 15 disk blocks)?
a) 24+600x10
b) 10+300x24
c) 24 + 2x10
d) 24 + 10
e) other value:
4
14)
Assume that we have 7 blocks of memory available for the hash join
operation. In how many steps can we partition a relation that occupies
100 blocks on disk such that it can be the build input of the partition
operation ?
a) 4
b) 3
c) 2
d) 1
e) other value:
15) Assume that we have 5 blocks of memory available for the merge-sort
operation. How many block accesses do we need to merge-sort a relation which occupies
111 blocks? Assume we also write back the result of the sort operation.
a) 111 x 2 x 3
b) 111 x 2 x 4
c) 111 x 2 x 5
d) (111  4) x 3 x 2
e) other value:
5
PART II: Indexing and Hashing
II-1)
Assume that each disk block can hold 2 records and hash function h(x) = (x mod 10) is
represented by 4 binary digits. For example, h(16)= 0110, h(2)=0010, h(31)=0001 etc.
Assuming that we use extendable hashing, show the hash structure after the insertion of
29 28 16 12 19 11 in the given order. Make sure you label the blocks with the number
of bits used. We need to see the hash structure after each insertion. (15 pts)
0
0
29
28
1
1
1
0
1
16
12
29
28
2
00
01
1
16
12
10
11
3
000
001
010
011
100
16
12
29
28
3
2
111
29
28
2
4
2
0000
12
11
4
0001
0010
0011
29
0100
16
1
4
0000
0001
0010
0011
0100
16
12
28
0101
0110
0111
1000
1001
0101
0110
0111
1000
100
101
110
1
101
110
2
4
1001
1010
1011
3
3
1010
1011
1100
2
1101
1110
1111
111
6
2
4
28
4
3
29
19
2
Assume in the questions below that tuples of the following relation r(A) with only
one attribute A appear in the given sequence r(A)=(3,2,11,14,41,12,33,25,76,5,16,8).
II-2)
An incomplete 2-level ordered secondary index on A for r(A) with 3 entries in the 2nd
level is given below.
Complete this structure by filling in the blank cells in the first and 2nd level indices,
assuming that numeration of tuples starts from 1 (10 pts).
Tuples of r(A):
A
3 2
11
14
41
12
33
25
76
5
16
8
Record №
1 2
3
4
5
6
7
8
9
10
11
12
1st level index
Ref
2
Key value
Record №
1
10
12
3
2
3
5
8
1
2
3
4
2nd level index
Ref
Key value
Record №
7
4
4
8
7
5
9
11 12
14
25
33
41
76
5
7
8
9
10
11
10
8
14
41
1
2
3
7
6
6
II-3)
An incomplete B+-tree is given below for r(A) with n=4. Each node is uniquely
identified by its number (below node, at right). Pointers to tuples in leaf nodes are
omitted for brevity.
a. Complete this structure up to full B+-tree using arrows and filling values in
appropriate places (10 pts).
| 14 | | | | |
1
| 5 | | 11 | |
| 33 | | | |
3
2
|2| |3| | |
4
|5 | | 8| | |
|11| |12| | |
5
6
|14| |16| |25|
|
7
|33| |41| |76 |
b. Write out the sequence of B+-tree nodes numbers, passed by while processing query
SELECT * FROM r WHERE A >= 4 and A<=15 (5 pts).
(1, 2, 4, 5, 6, 7)
8
8
II-4)
An incomplete schema reflecting the process of sorting r(A) using the external sortmerge algorithm is given below, assuming that memory buffer has only 3 pages, each of
which can hold only 1 tuple (so, number of pages for r(A) is 12).
Complete this schema by drawing the necessary frames, filling them by appropriate
values and connecting them by appropriate arrows (15 pts).
2
3
11
3
2
11
12
14
14
41
2
3
11
12
14
41
41
12
3
5
8
11
12
33
25
25
76
33
76
5
16
8
2
5
8
5
8
16
25
33
76
16
*************************** The End ****************************
9
14
16
25
33
41
76