Apache Spark Spark Streaming 3

Question 1

What is a sliding window in Spark Structured Streaming?

Accepted Answer

A window that moves forward by a fixed step smaller than the window duration, causing overlaps

Answer

A sliding window has a duration and a slide interval; if the slide is smaller than the window duration, windows overlap.

Question 2

Which method starts a streaming query in Spark Structured Streaming?

Accepted Answer

df.writeStream.start()

Answer

writeStream configures the output sink and options, and start() launches the streaming query, returning a StreamingQuery object.

Question 3

What is the Update output mode in Spark Structured Streaming?

Accepted Answer

Writes only rows that were updated or newly added since the last trigger

Answer

Update mode writes only the rows in the result table that were changed (inserted or updated) since the last trigger.

Question 4

Which method waits for a streaming query to finish in Spark?

Accepted Answer

query.awaitTermination()

Answer

awaitTermination() blocks the driver program until the streaming query is stopped or encounters an error.

Question 5

What is the role of offsets in Spark Structured Streaming with Kafka?

Accepted Answer

They track the position in the Kafka topic for fault-tolerant exactly-once processing

Answer

Offsets track the last-read position in Kafka topics, stored in checkpoints, enabling the stream to resume from where it stopped.

Apache Spark Practice Test