Introduction Lazy evaluation means the execution will not start until anaction is triggered. Transformations are lazy in nature i.e. when we call some operation on RDD, it does not execute immediately. Spark adds them to a DAG of computation and only when driver requests some data, this DAG actually gets executed
Advantages of lazy evaluation.
1) It is an optimization technique i.e. it provides optimization by reducing the number of queries.
2) It saves the round trips between driver and cluster, thus speeds up the process.