def rdd: RDD[T]
RDD Dependencies
Dependency
class is the base (abstract) class to model a dependency relationship between two or more RDDs.
Dependency
has a single method rdd
to access the RDD that is behind a dependency.
Whenever you apply a transformation (e.g. map
, flatMap
) to a RDD you build the so-called RDD lineage graph. Dependency
-ies represent the edges in a lineage graph.
Note
|
NarrowDependency and ShuffleDependency are the two top-level subclasses of Dependency abstract class.
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Name | Description |
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Note
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The dependencies of a RDD are available using dependencies method.
You use toDebugString method to print out the RDD lineage in a user-friendly way.
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