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

c. Unlock(X)
90. elaborate the phases in a locking transaction?
a. Expanding phase
b. Shrinking Phase
91. describe deadlock
Deadlock occurs when every transaction T in a set of 2 or more transactions is
waiting for a few item that is locked by a few other transaction T in the set.
92. describe a Timestamp
A time stamp is a unique identifier created by the DBMS to identify a transaction.
93. elaborate the values current in a timestamp algorithm?
a. learn TS(X)
b. Write TS(X)
94. elaborate the phases in concurrency control protocol?
a. learn phase
b. Validation phase
c. Write phase
95. elaborate the conditions that hold in a validation phase?
a. Transaction Tj completes its write phase before Ti begins its learn phase
b. Ti begins write phase after Tj completes its write phase and the learn set of Ti
has no items in common with the write set of Tj
c. Both the learn set and the write set of Ti have no items in common with the
write set of Tj and Ti completes its learn phase before Ti completes its learn
phase
96. describe granularity?
The size of data item is called data item granularity.
97. elaborate kinds of intension locks?
a. Intension shared
b. Intension Exclusive
c. Shared-Intension Exclusive
98. elaborate the techniques for recovery from non catastrophic failures?
a. Deferred update
b. Immediate update
99. describe directory?
A directory for the cache is used to keep track of which database items are in the
buffers.
100. What is a dirty bit?
It shows whether or not the buffer has been modifies.
Sixteen Marks ques. and Answers
1. Explain: Data models, Schemas, and Instances
a) Categories of data models
A database management system is a collection of programs that enables users to
create and maintain a database.
b) Schemas, Instances, and Database state
c) self describing nature of the database
d) insulation ranging from programs and data and data abstraction.
e) Support for multiple views of data
f) Sharing of data and multi-user transaction processing
2. Explain: DBMS architecture and data independence
a) The three-schema architecture
A data model is a collection of concepts that can be used to define the structure

Earning:   Approval pending.