Subject Syllabus Hub3+ MCQs3 Topics

Database Management Systems

Relational database architecture, relational algebra, SQL optimization, ACID properties, transaction management, and indexing strategies.

Topic Syllabus & Revision Notes

High-yield concept summaries, formulas, and common exam pitfalls for each topic.

Topic 14 Key Rules

ACID Properties & Atomicity

ACID guarantees form the bedrock of transactional database systems. Atomicity ensures that if an error occurs midway through a transaction (e.g. money deducted from Account A but system crashes before crediting Account B), the database engine automatically rolls back all changes so no partial updates remain.

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Topic 24 Key Rules

B+ Trees & Disk Indexing

In relational databases (like PostgreSQL, MySQL, Oracle), B+ Trees are the gold standard for disk indexing. Unlike standard B-Trees where data pointers are scattered across internal nodes, B+ Trees store all record pointers in leaf nodes. Because the leaf nodes are linked sequentially, scanning a range of keys (e.g., `WHERE age BETWEEN 20 AND 30`) simply traverses the leaf linked list without re-traversing the tree structure.

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Topic 34 Key Rules

Normal Forms & BCNF

Database normalization organizes attributes to reduce data redundancy and update anomalies. BCNF addresses functional dependencies where a non-prime or prime attribute is functionally determined by a non-superkey. By enforcing that every determinant X in X -> Y must be a superkey, BCNF eliminates all redundancy based on FDs.

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High-Yield Practice Questions

Sample practice MCQs with step-by-step verified explanations.

Problem #1MEDIUM

Why are B+ Trees preferred over B-Trees for disk-based database indexing?

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Problem #2MEDIUM

Which ACID property guarantees that either all operations of a database transaction are executed or none of them are?

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Problem #3MEDIUM

A relation R is in Boyce-Codd Normal Form (BCNF) if for every non-trivial functional dependency X -> Y, which condition must hold?

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