DBMS Exam Notes

Definition of data, database and database management systems. Discussion of application and significance of databases and DBMS. History of databases and evolution to recent trends.

Description and significance of data models. Brief description and illustrative example of each type: Entity-relationship, relational, object model, hierarchical, network, and graph data models.

Description and usage of relational algebra operators with examples. Selection (σ), projection (π), Cartesian product (×), various types of join (⋈), rename (ρ). Set operations: union (∪), intersection (∩), difference (−). Modification of relations with assignment operator. Example queries and practice problems.

NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, and CHECK constraints with SQL syntax. Relational integrity and key constraints. Domain constraints.

Description and significance of query processing and optimization. Stages of query processing: parsing, translation to relational algebra, optimization, evaluation. Block diagram of the query processing pipeline.

Physical storage media: magnetic disk, SSD, optical, tape. Storage hierarchy. RAID levels (0–6): striping, mirroring, parity. Selecting an appropriate RAID level.

Definition and significance of transactions with practical examples. States: Active, Partially Committed, Committed, Failed, Aborted. State-transition diagram.

Transaction failure (logical error, system error). System crash (power failure, hardware fault). Disk failure. Stable storage concept and implementation.

Object-based database concepts: encapsulation, inheritance, polymorphism, object identity. Object-relational data model. Complex data types: collections, nested relations. Persistence. Object-relational mapping (ORM).