Data Processing Computer-Based Test On Data-Processing 5 — Questions and Answers
Question 1: Which of the following is a characteristic of columnar storage compared to row-based storage?
- Faster for inserting individual records
- Better performance for analytical queries that aggregate a few columns across many rows (Correct answer)
- Lower storage overhead for transactional workloads
- Simpler to implement for OLTP systems
Correct answer: Better performance for analytical queries that aggregate a few columns across many rows
Columnar storage groups values of the same column together, so analytical queries that read only a few columns can skip irrelevant data.
Question 2: In data processing, 'idempotency' means that an operation:
- Executes faster on repeated calls
- Produces the same result whether applied once or multiple times (Correct answer)
- Requires a unique transaction ID for each execution
- Automatically rolls back on failure
Correct answer: Produces the same result whether applied once or multiple times
An idempotent operation yields the same outcome regardless of how many times it is applied, which is critical for safe retries in distributed systems.
Question 3: Which processing model does Apache Kafka primarily support?
- Batch processing of fixed-size files
- Real-time event streaming and message queuing (Correct answer)
- In-memory relational query processing
- Graph traversal and network analysis
Correct answer: Real-time event streaming and message queuing
Apache Kafka is a distributed event-streaming platform designed for high-throughput, low-latency publishing and subscribing to real-time data streams.
Question 4: A 'surrogate key' in a data warehouse is best described as:
- The natural business key imported from a source system
- A system-generated artificial key used to uniquely identify dimension records (Correct answer)
- A composite key made from multiple business attributes
- A foreign key that references the fact table
Correct answer: A system-generated artificial key used to uniquely identify dimension records
Surrogate keys are integer identifiers assigned by the warehouse system, independent of source system keys, to handle slowly changing dimensions and key conflicts.
Question 5: In data compression, which technique identifies repeated patterns and replaces them with shorter codes?
- Encryption
- Normalization
- Run-length encoding (Correct answer)
- Hashing
Correct answer: Run-length encoding
Run-length encoding (RLE) compresses data by replacing consecutive repeated values with a single value and a count.
Question 6: What is the role of a 'data steward' in an organization's data governance framework?
- Writing SQL queries for the analytics team
- Ensuring data quality, consistency, and proper use of data assets within a domain (Correct answer)
- Administering database server hardware and backups
- Developing ETL pipelines for data integration
Correct answer: Ensuring data quality, consistency, and proper use of data assets within a domain
A data steward is accountable for the accuracy, integrity, and appropriate use of data within their assigned business domain.
Question 7: Which type of join returns all rows from both tables, filling in NULLs where there is no match?
- INNER JOIN
- LEFT JOIN
- RIGHT JOIN
- FULL OUTER JOIN (Correct answer)
Correct answer: FULL OUTER JOIN
A FULL OUTER JOIN returns every row from both tables; where no match exists on either side, NULL values fill the missing columns.
Data Processing Computer-Based Test On Data-Processing 5
Which of the following is a characteristic of columnar storage compared to row-based storage?