PySpark and AWS: Master Big Data with PySpark and AWS - RDD ReduceByKey

The video tutorial explores the concept of 'reduce by key' in RDDs, explaining how it combines data based on keys and contrasts it with 'group by key'. It details the syntax and use of Lambda functions for reduction, providing a practical example to illustrate the process. The tutorial concludes by summarizing the key differences between the two methods, emphasizing the need for a reduction mechanism in 'reduce by key'.

What is the primary purpose of 'reduce by key' in Spark RDD?

• To filter data based on keys

• To combine data based on keys

• To duplicate data based on keys

• To sort data based on keys

Which of the following is a key difference between 'reduce by key' and 'group by key'?

• Neither requires a function for aggregation.

• 'Reduce by key' requires a function for aggregation, while 'group by key' does not.

• 'Group by key' requires a function for aggregation, while 'reduce by key' does not.

• Both require a function for aggregation.

What is the role of a lambda function in 'reduce by key'?

• To sort the keys

• To duplicate the values

• To define how values are combined

• To filter out unwanted keys

How does 'reduce by key' handle data differently from 'group by key'?

• Both sum the values.

• Both create a list of values.

• 'Group by key' creates a list of values, while 'reduce by key' sums them.

• 'Reduce by key' creates a list of values, while 'group by key' sums them.

In the context of 'reduce by key', what does the lambda function return?

• A list of keys

• A single combined value

• A duplicated list of values

• A sorted list of values

What happens if you do not provide a function to 'reduce by key'?

• It will group the values by default.

• It will filter out duplicate keys.

• It will raise an exception.

• It will automatically sum the values.

Which of the following best describes the output of 'reduce by key'?

• A duplicated list of keys

• A list of all keys and their values

• A single value for each key

• A sorted list of keys

What is the expected output when using 'reduce by key' with a summing function?

• A list of summed values for each key

• A single summed value for each key

• A list of keys without values

• A list of values without keys

Why is it important to ensure the input is in key-value format for 'reduce by key'?

• To ensure the keys are sorted

• To filter out unwanted keys

• To duplicate the values

• To allow proper aggregation of values

What is a common mistake beginners make when using 'reduce by key'?

• Not providing a function for reduction

• Using it to sort keys

• Using it to filter values

• Duplicating the keys