(SEM V) THEORY EXAMINATION 2021-22 DATABASE MANAGEMENT SYSTEM

DATABASE MANAGEMENT SYSTEM (KCS-501)

B.Tech (Sem V) – Exam Notes & Answers

SECTION A – Short Answer Type (2 Marks Each)

a. Significance of Physical Data Independence
Physical data independence allows changes in the physical storage of data without affecting the logical schema or application programs.

b. Functions of DBA (Any Four)
Database design, user authorization, performance tuning, backup and recovery, and security management.

c. Recursive Relationship Set
A relationship set is called recursive when an entity participates more than once in a relationship with itself.

d. Currency in Database
Currency refers to how up-to-date and consistent the data in a database is at a given time.

e. Relational Calculus
Relational calculus is a non-procedural query language that specifies what data to retrieve rather than how to retrieve it.

f. Equi-Join
An equi-join is a join operation that uses equality conditions between attributes of two relations.

g. Clause in SQL
A clause is a component of an SQL statement such as WHERE, GROUP BY, HAVING, or ORDER BY.

h. Closure of an Attribute Set
Attribute closure is the set of all attributes functionally determined by a given attribute set.

i. Transaction Rollback
A transaction is rolled back when an error occurs or consistency is violated, restoring the database to its previous state.

j. Levels of Locking
Row-level, page-level, table-level, and database-level locking.

SECTION B – Descriptive Answers (10 Marks Each)

Overall Structure of DBMS

A DBMS consists of query processor, storage manager, transaction manager, data dictionary, and database engine. These components work together to store, retrieve, and manage data efficiently.

Union Compatibility in Relational Algebra

Operations like UNION, INTERSECTION, and DIFFERENCE require union-compatible relations, meaning they must have the same number of attributes and corresponding domains.

Transitive Dependency

A transitive dependency occurs when a non-prime attribute depends on another non-prime attribute.
It leads to insertion, deletion, and update anomalies.

ACID Properties

Atomicity ensures all-or-nothing execution, Consistency maintains database rules, Isolation avoids interference, and Durability ensures permanent storage.
The log helps in recovery and maintaining consistency.

Time-Stamping Protocol & Multi-Version Scheme

Time-stamping assigns a unique time stamp to each transaction to maintain serializability.
Multi-version concurrency control keeps multiple versions of data to allow concurrent access.

SECTION C – Long Answer Type

Data Models in DBMS

Types include hierarchical, network, relational, object-oriented, and object-relational data models.

Procedural vs Non-Procedural DML

Procedural DML specifies how to retrieve data, while non-procedural DML specifies what data is required.

SQL & Relational Algebra Queries (Library Schema)

Queries involve selection, projection, join, and condition filtering to retrieve student and book information.

Triggers

A trigger is a database object that automatically executes in response to insert, update, or delete operations.

Armstrong’s Axioms

These include reflexivity, augmentation, and transitivity rules, used to infer functional dependencies.

Multivalued Dependency (MVD), 4NF & 5NF

MVD occurs when attributes are independent of each other.
4NF removes MVDs, and 5NF removes join dependencies.

Serializable Schedule & Conflict Serializability

A schedule is serializable if it produces the same result as a serial schedule. Conflict serializability is checked using precedence graphs.

Deadlock Detection & Recovery

Deadlocks are detected using wait-for graphs and resolved by aborting or rolling back transactions.

Schedule Equivalence Problem

Given schedule operations are analyzed for conflict equivalence to determine serializability.

Two-Phase Commit (2PC) Protocol

2PC ensures distributed transaction consistency using prepare and commit phases.
Validation-based protocols differ by checking transactions before committing.