Apache Spark RDD operations : Transformations and Actions
Автор: BigDataElearning
Загружено: 2017-04-13
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Official Website: http://bigdataelearning.com
RDD operations
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There are 2 operations that can be applied on RDD. One is transformation.
1) Transformation
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Transformation is what you do to an RDD to get another resultant RDD.
The example would be to apply functions like filter, union , that would then create another resultant RDD.
FILTER is a transformation that when applied on an RDD, will isolate certain elements and create a new RDD.
This combining of elements from 2 RDD be done using UNION transformation. UNION is a multi-RDD transformation, which means it acts on more than one RDD.
2) Actions
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Actions are second type of operations in RDD. Actions return a result to the driver program , or write it in a storage and kick off a computation. some examples are count , first, collect, take
count action can be used to get the number of elements in an RDD.
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first action can be used to retrieve the first element in the RDD.
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take action can be used to retrieve n elements out of the RDD.
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collect action can be used to retrieve the complete list of elements
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from the RDD.
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