Noorul Islam University 2008 M.Sc Software Engineering XCS 235 – DATABASE MANAGEMENT SYSTEMS - Question Paper

b) Secondary storage
32. describe track.
every concentric circle in a disk surface is called a track.
33. What is the hardware address of a block?
The hardware address of a block is the combination of a surface number, track
number and block number.
34. describe seek time.
To transfer a disk block, provided its address, the disk controller must 1st position
the learn write head on the accurate track. The time needed to do this is called
seek time.
35. describe rotational delay or latency
The beginning of the desired block rotates into position under the learn write head
is called rotational delay or latency.
36. describe block transfer time.
Time needed to transfer the data is called block transfer time.
37. describe bulk transfer rate
The time needed to transfer consecutive blocks is called bulk transfer rate.
38. What is data striping
Data striping distributes the data transparently over multiple disks to make them
appear as a single large fast disk.
39. What is mirroring or shadowing?
Data is written redundantly to 2 identical physical disks that are treated as one
logical disk. When data is learn it can be retrieved from the disk, with short
queuing, seek time and rotational delay.
40. What is bit level data striping?
Bit level data striping consists of splitting a byte of data and writing bit j to the jth
disk.
41. elaborate the records-at a time operations?
Reset, find, read, findnext, delete, modify, insert
42. elaborate the set at a time operations?
Findall, Findordered, reorganize.
43. describe hashing function?
It provides a function h called the hash function that is applied to the hash field
value of a record and yields the address of the disk block in which the record is
stored.
44. What is folding?
It involves applying an arithmetic function such as addition or logical function
such as exclusive or to various portions of the hash field value to compute the
hash address.
45. When does collision occur?
A collision occurs when a hash field value of a record that is being inserted
hashes to an address that already contains a various record.
46. What is collision resolution?
The process of finding new location to insert record is called collision resolution.
47. State the methods of collision resolution?

Earning:   Approval pending.