Anomalies & Denormalization in DBMS

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Question 1

What is an insertion anomaly?

  • A new row is added but triggers a deletion

  • Data cannot be inserted due to missing referenced data

  • A row is inserted without foreign key

  • A duplicate row is inserted

Question 2

What causes deletion anomalies in a relational model?

  • When a record is deleted from a primary table only

  • When deleting a row results in losing useful unrelated information

  • When deleting a foreign key from referencing table

  • When deleting all records with NULL values

Question 3

What is an update anomaly?

  • When updates are disallowed in a table

  • When data becomes inconsistent after an update

  • When a foreign key is updated to NULL

  • When an update triggers a rollback


Question 4

Which of the following is most effective in removing anomalies from a database?

  • Indexing

  • Hashing

  • Normalization

  • Views

Question 5

Which SQL keyword helps automatically handle anomalies in foreign key relations?

  • CHECK

  • CONSTRAINT

  • ON DELETE/UPDATE

  • NOT NULL

Question 6

Which of the following is the primary objective of performing Denormalization in a database?

(GATE 2021 | MCQ | 1-Mark)

  • To eliminate all redundant data and functional dependencies

  • To improve the performance of read-intensive queries by reducing the number of joins

  • To ensure the database strictly adheres to the Domain-Key Normal Form (DKNF)

  • To increase the speed of INSERT and UPDATE operations by simplifying the table structure

Question 7

In which of the following scenarios is Denormalization most likely to be preferred over high levels of Normalization?

(GATE 2021 | MCQ | 1-Mark)

  • A banking system where data consistency and atomicity of transactions are the highest priority

  • A real-time inventory system where stock levels are updated thousands of times per second

  • A reporting dashboard for an e-commerce site that aggregates millions of historical sales records

  • A metadata repository that requires strict adherence to 5NF to prevent join dependencies

Question 8

Which of the following operations is commonly reduced through denormalization?

  • Projection

  • Selection

  • Join

  • Aggregation

Question 9

Which of the following best differentiates normalization and denormalization?

  • Normalization increases query speed; denormalization decreases it

  • Normalization removes redundant data; denormalization adds it for performance

  • Normalization is used only in NoSQL databases

  • Denormalization ensures referential integrity

Question 10

In which scenario is denormalization most beneficial?

  • When updates are frequent

  • When data changes frequently

  • When reads are frequent and joins are expensive

  • When memory usage must be minimized

There are 10 questions to complete.

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