MS-DS Master of Data science Big Data 3

Question 1

Which technique does Apache Spark use to optimize query execution plans in Spark SQL?

Accepted Answer

Catalyst optimizer

Answer

Spark SQL uses the Catalyst optimizer to apply rule-based and cost-based optimizations on logical and physical query plans.

Question 2

In stream processing, what does 'exactly-once' semantics guarantee?

Accepted Answer

Each message produces one and only one output effect

Answer

Exactly-once semantics ensures that despite failures and retries, each input message affects system state only once.

Question 3

Which data format is columnar and widely used in the Hadoop ecosystem for efficient analytical queries?

Accepted Answer

Parquet

Answer

Parquet is a columnar storage format that enables efficient column pruning and predicate pushdown for analytical queries.

Question 4

What is the primary role of Apache ZooKeeper in a distributed big data system?

Accepted Answer

Distributed coordination and consensus

Answer

ZooKeeper provides distributed coordination services such as leader election, configuration management, and distributed locks.

Question 5

Which windowing strategy in stream processing assigns each event to all windows that contain its timestamp?

Accepted Answer

Sliding window

Answer

Sliding windows overlap, so a single event can belong to multiple windows depending on the slide interval.

MS-DS Master of Data science Practice Test