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

on their FDs and primary keys to decrease redundancy and to minimize insertion,
deletion and updation.
64. What is a prime attribute?
An attribute of relation schema R is called prime attribute of Red if it is a
member of a few candidate key of R.
65. describe full functional dependency.
If the removal of any attribute A from X means that the dependency does not
hold any more.
66. elaborate the 2 techniques of implementing query optimization?
a. Heuristic rules for ordering the operations in a query execution strategy
b. Systematically estimating the cost of various execution strategies
67. describe external sorting?
It refers to sorting algorithms that are suitable for large files of records stored on
disk that do not fit entirely in main memory such as most database files.
68. elaborate the phases of external sorting?
a. Sorting phase
b. Merging phase
69. describe degree of merging?
It is the number of runs that can be merged together in every pass.
70. provide the search methods for simple choose operation?
a. linear search
b. Binary Search
c. Using a primary index
d. Using a primary index to retrieve multiple records
e. Using a clustering index to retrieve multiple records
f. Using secondary index on equality comparison
71. elaborate the methods for implementing joins?
a. Nested loop join
b. Single loop join
c. Sort-merge join
72. What is a query tree?
A query tree is a data structure that corresponds to a relational algebra expression.
It represents the input relations of the query as leaf nodes of the tree, and
represents the relational algebra operations as internal nodes.
73. elaborate the cost components for query execution?
a. Access cost to secondary storage
b. Storage cost
c. calculation cost
d. Memory usage cost
e. Communication cost
74. describe selectivity?
Selectivity is the fraction of records satisfying an equality condition on the
attribute.
75. describe selection cardinality?
It is the avg. number of records that will satisfy an equality selection
condition on that attribute.
76. describe transaction
A transaction is a logical unit of database processing that includes 1 or more
database access operations that include insertion, deletion, modification or

Earning:   Approval pending.