What is the default transformation class for hadoop ​

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The default is the following conversion class

Job.setInputFormatClass (TextInputFormat.class)

The List InputFormat.getSplits first splits the input data, and the split split decides the number of tasks of the map in writing.

RecordReader InputFormat.createRecordReader (InputSplit split,...) Pass in the segmented data, process it into key and value, and then send the keyvalue value to map for execution. Each pair of key and value pairs will call map.

FileInputFormat extends InputFormat

List FileInputFormat.getSplits

TextInputFormat extends FileInputFormat

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