NielsenIQ Lead Data Engineer Interview Questions and Answers

List is an ordered collection of elements with duplicates allowed, while set is an unordered collection of unique elements.

• List maintains the order of elements, while set does not guarantee any specific order.

• List allows duplicate elements, while set does not allow duplicates.

• Example: List - [1, 2, 3, 1], Set - {1, 2, 3}

Optimizing PySpark involves tuning configurations, using efficient transformations/actions, and leveraging caching.

• Tune PySpark configurations for optimal performance (e.g. adjusting memory settings, parallelism)

• Use efficient transformations/actions to minimize unnecessary data shuffling (e.g. using narrow transformations like map instead of wide transformations like groupByKey)

• Leverage caching to persist intermediate ...read more

SOLID principles are a set of five design principles in object-oriented programming to make software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable...read more