Lineage of RDD

RDD tracking 

Every RDD keeps track of :

1. where it came from ?
2.  All transformation it took to reach it's current state

These steps are called Lineage/DAG of an RDD



Data Visualization

• In Spark, a job is associated with a chain of RDD dependencies organized in a direct acyclic graph (DAG)
• Dependency graph where every RDD knows its parent RDD and the transformation

Note: All transformation are in memory and none of the transformation are
applied till we access the results

Advantage of Lineage

• Allows RDD's to be reconstructed when nodes crash.
• We start from the source file. Apply all the transformation which are stored and recreate the RDD
• Allows RDD's to be lazily instantiated (materialized) when accessing the results