CCP Database Management & Information Systems 3

Question 1

Which concurrency control technique uses shared and exclusive locks to prevent conflicting database operations?

Accepted Answer

Two-phase locking (2PL)

Answer

Two-phase locking grants shared locks for reads and exclusive locks for writes, releasing them only after the transaction commits.

Question 2

A view in a relational database is best described as:

Accepted Answer

A virtual table based on a stored SQL query

Answer

A view is a named, stored SELECT statement that presents data from one or more tables without storing the data itself.

Question 3

Which data model represents data as a collection of nodes and edges, making it ideal for social networks and recommendation engines?

Accepted Answer

Graph model

Answer

Graph databases store data as nodes (entities) and edges (relationships), efficiently traversing highly connected datasets.

Question 4

What does the ACID property 'Isolation' guarantee?

Accepted Answer

Concurrent transactions do not interfere with each other

Answer

Isolation ensures that the intermediate state of a transaction is invisible to other concurrently running transactions.

Question 5

In database design, what is a surrogate key?

Accepted Answer

A system-generated, meaningless unique identifier

Answer

A surrogate key is an artificially generated identifier (e.g., auto-increment integer) with no business meaning.

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