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Question 11

Which KSQL function is used to concatenate two strings?

  • A. CONCAT()
  • B. JOIN()
  • C. MERGE()
  • D. APPEND()

Explanation: The CONCAT() function in KSQL is used to concatenate two strings.

  • B, C, and D are incorrect because they are not valid KSQL functions for concatenating strings.

Answer: A

Question 12

What is the role of the KEY keyword in KSQL table creation?

  • A. To define the primary key of the table
  • B. To specify the partitioning key of the table
  • C. To assign a unique identifier to each record
  • D. To create an index on the table

Explanation: The KEY keyword in KSQL table creation is used to specify the primary key of the table, which is also used for partitioning.

  • B, C, and D are incorrect because they do not accurately describe the role of the KEY keyword in KSQL.

Answer: A

Question 13

Which statement is true about KSQL streams?

  • A. They store historical data indefinitely
  • B. They are append-only collections of immutable records
  • C. They can be directly queried for the current state
  • D. They do not support windowed aggregations

Explanation: KSQL streams are append-only collections of immutable records that represent the continuous flow of data.

  • A, C, and D are incorrect because streams do not store data indefinitely, they represent immutable records, and they do support windowed aggregations.

Answer: B

Question 14

Which KSQL command is used to terminate a running query?

  • A. DROP QUERY
  • B. STOP QUERY
  • C. TERMINATE
  • D. DELETE QUERY

Explanation: The TERMINATE command is used to stop a running query in KSQL.

  • A, B, and D are incorrect because they are not valid commands for terminating a query in KSQL.

Answer: C

Question 15

What is the result of executing the following KSQL query: SELECT * FROM my_stream EMIT CHANGES;?

  • A. It creates a new table from the stream
  • B. It continuously outputs the current state of the stream
  • C. It returns a snapshot of the stream at a point in time
  • D. It filters records based on a condition

Explanation: The SELECT * FROM my_stream EMIT CHANGES; query continuously outputs the current state of the stream, providing a real-time view of the data as it arrives.

  • A, C, and D are incorrect because they do not describe the behavior of the EMIT CHANGES clause.

Answer: B

Question 16

Which clause in KSQL is used to define the duration of a hopping window?

  • A. SIZE
  • B. DURATION
  • C. HOP
  • D. WINDOW

Explanation: The SIZE clause is used to define the duration of a hopping window in KSQL.

  • B, C, and D are incorrect because they are not valid clauses for defining the duration of a hopping window in KSQL.

Answer: A

Question 17

How can you perform an inner join between two streams in KSQL?

A. CREATE STREAM new_stream AS SELECT * FROM stream1 INNER JOIN stream2 WITHIN 5 MINUTES ON stream1.key = stream2.key;

B. CREATE STREAM new_stream AS SELECT * FROM stream1 JOIN stream2 ON stream1.key = stream2.key;

C. CREATE STREAM new_stream AS SELECT * FROM stream1 LEFT JOIN stream2 WITHIN 5 MINUTES ON stream1.key = stream2.key;

D. CREATE STREAM new_stream AS SELECT * FROM stream1 CROSS JOIN stream2 ON stream1.key = stream2.key;

Explanation:

The correct syntax to perform an inner join between two streams in KSQL is:

Option A:

CREATE STREAM new_stream AS
SELECT *
FROM stream1
INNER JOIN stream2
WITHIN 5 MINUTES
ON stream1.key = stream2.key;
  • INNER JOIN: Specifies that an inner join is to be performed between stream1 and stream2.
  • WITHIN 5 MINUTES: Defines a time window of 5 minutes for the join. This is mandatory for stream-to-stream joins in KSQL to handle the temporal nature of streaming data.
  • ON stream1.key = stream2.key: The join condition based on matching keys.

Option B is incorrect because it lacks the WITHIN clause, which is required when performing stream-to-stream joins in KSQL. Without the WITHIN clause, the join operation cannot properly align the streaming data over time.

Option C is incorrect because it uses a LEFT JOIN, which performs a left outer join, not an inner join. This means it would include all records from stream1 and the matching records from stream2, which is not the same as an inner join.

Option D is incorrect because CROSS JOIN is not supported between streams in KSQL. Additionally, even if it were, a cross join produces the Cartesian product of the two streams, which is not an inner join.

Answer:

A. CREATE STREAM new_stream AS SELECT * FROM stream1 INNER JOIN stream2 WITHIN 5 MINUTES ON stream1.key = stream2.key;

Question 18

What does the GROUP BY clause do in a KSQL query?

  • A. It filters records based on a condition
  • B. It partitions the data by a specified key
  • C. It aggregates data based on specified columns
  • D. It orders the data by a specified column

Explanation: The GROUP BY clause in a KSQL query aggregates data based on specified columns, allowing for calculations like COUNT, SUM, AVG, etc., over grouped records.

  • A, B, and D are incorrect because they describe different functionalities in KSQL.

Answer: C

Question 19

Which keyword is used to create a persistent query in KSQL?

  • A. PERSIST
  • B. CREATE STREAM AS
  • C. CREATE PERSISTENT QUERY
  • D. SAVE

Explanation: The CREATE STREAM AS keyword is used to create a persistent query in KSQL. This query continuously processes the data and stores the results in a new stream.

  • A, C, and D are incorrect because they are not valid keywords for creating a persistent query in KSQL.

Answer: B

Question 20

Which function is used to calculate the number of records in a KSQL stream?

  • A. COUNT()
  • B. SUM()
  • C. AVG()
  • D. MAX()

Explanation: The COUNT() function is used to calculate the number of records in a KSQL stream.

  • B, C, and D are incorrect because they perform different types of calculations.

Answer: A