Apache Spark

Correct Answer: To read text data from a file into an RDD

The textFile() method is used to read text data from a file into an RDD. It takes a path to the file as its argument and returns a new RDD that contains the lines of the file as its elements.

Correct Answer: Caches an RDD or DataFrame in memory or disk storage to allow for faster access

The 'persist()' operation in Spark is used to cache an RDD or DataFrame in memory or disk storage to allow for faster access. Caching an RDD or DataFrame can significantly improve the performance of iterative and interactive algorithms that access the same data multiple times. Once an RDD or DataFrame is persisted in memory, subsequent operations that use that RDD or DataFrame can access the data faster than if it were read from disk or network storage. Persistent storage options include MEMORY_ONLY, MEMORY_ONLY_SER, MEMORY_AND_DISK, DISK_ONLY, etc.

Correct Answer: Returns the first n elements of an RDD or DataFrame

The 'take()' operation in Spark is used to return the first n elements of an RDD or DataFrame. This operation is useful for quickly previewing the contents of an RDD or DataFrame, or for retrieving a small subset of data for further processing. The number of elements to return is specified as an argument to the 'take()' method. If no argument is provided, the default value of 1 is used.