Understanding Various Spark Actions

Spark actions trigger specified transformations. Transformations create RDDs from another RDD. Actions are the operations that are performed on RDDs to give non-RDD values.

Popular actions include reduce, collect, count, first, and s. Actions are executed and values of actions are stored back in Spark drivers or external storage systems.

Let's understand transformations in more detail:

• reduce(func): This aggregates the elements of a dataset by executing a function on them. reduce works only with commutative and associative functions as it runs in parallel. For example, reduce could be taking (a, b) as the two inputs and having a+b as one output. Say if the input data is {1,2,…100}, using the sum function on reduce would result in {5050}, which is the sum of all the elements of the dataset.
• collect(): This returns all the elements in a dataset. This is the equivalent of select * in SQL. For example, if the dataset...