Midterm

Question 1

Disk Capacity

Answer 1

Hard Drive Size

Question 2

Access Time

Answer 2

Time from request to start of data transfer

Question 3

Seek Time

Answer 3

Time for arm to reach track

Question 4

Rotational Latency

Answer 4

Time for sector to appear under head

Question 5

Transfer Time

Answer 5

Time to transfer data to memory

Question 6

Disk arm scheduling algorithm purpose

Answer 6

Minimizes arm movement

Question 7

Buffering purpose

Answer 7

Temporary storage for satisfying future requests

Question 8

Mean Time to Data Loss dependencies

Answer 8

MTTF and MTTR (repair)

Question 9

Cylinder

Answer 9

Track for all the platters in a disk. 10 tracks, 10 cylinders. Cylinder i contains ith track of all platters

Question 10

Disk Controller

Answer 10

Interfaces between software and hardware

Question 11

Block

Answer 11

Contiguous sequence of sectors from a single track. Smaller blocks result in more transfers, larger blocks result in wasted space.

Question 12

RAID 0

Answer 12

Block striping, non-redundant. Good for high performance where data loss is acceptable.

Question 13

RAID 1

Answer 13

Block striping with mirroring. Good for write-heavy applications, ex. logging.

Question 14

RAID 3

Answer 14

Bit interleaved parity. Using a parity bit disk. Data can be recovered using XOR. Good for data transfer, not ideal for I/O. Not used often since single block reads need to access all disks.

Question 15

RAID 4

Answer 15

Block interleaved parity. Block level striping. Keeps parity on a separate disk. Better I/O than RAID 3, but typically 5 is used over 4.

Question 16

RAID 5

Answer 16

Block interleaved distributed parity. Partitions data and parity among all N+1 disks. Good for low update rates with large amounts of data.

Question 17

RAID 6

Answer 17

P + Q Redundancy. Similar to 5 but with redundant information to protect against multiple disk failures. Growing in popularity.

Question 18

Default SQL Deletion Strategy if referenced elsewhere

Answer 18

Rejection

Question 19

Cascade Delete

Answer 19

Delete from tables where appears

Question 20

5 + Null =

Answer 20

Null

Question 21

Null or True

Answer 21

True

Question 22

Null or False

Answer 22

Null

Question 23

Null or Null

Answer 23

Null

Question 24

True and Null

Answer 24

Null

Question 25

False and Null

Answer 25

False

Question 26

Null and Null

Answer 26

Null

Question 27

Not Null

Answer 27

Null

Question 28

Aggregate functions

Answer 28

sum, average, min, max, count

Question 29

DDL

Answer 29

Data Definition Language. Schema and ICs

Question 30

DML

Answer 30

Data Manipulation Language. Query, insert, delete, updateas

Question 31

What is a good tradeoff between dense and sparse indexes?

Answer 31

Sparse index with an entry at each block. Searching the block is trivial.

Question 32

Primary index

Answer 32

Specified sequential order of file. Usually the primary key.

Question 33

Secondary Index

Answer 33

Search key is different from sequential order. Must be dense

Question 34

Multilevel index

Answer 34

Treat primary index as a sequential file and construct a sparse index on it

Question 35

Index Deletion

Answer 35

Dense - Similar to record deletion. Sparse - If search key is in index, replace with next in order if not already associated with a search key. Else delete the index entry.