Cloudera
CCD-333 · Question #54
You write a MapReduce job to process 100 files in HDFS. Your MapReducc algorithm uses TextInputFormat and the IdentityReducer: the mapper applies a regular expression over input values and emits…
The correct answer is C. With zero reducers, all instances of matching patterns are gathered together in one file on. See the full explanation below for the reasoning.
Question
You write a MapReduce job to process 100 files in HDFS. Your MapReducc algorithm uses TextInputFormat and the IdentityReducer: the mapper applies a regular expression over input values and emits key-value pairs with the key consisting of the matching text, and the value containing the filename and byte offset. Determine the difference between setting the number of reducers to zero.
Options
- AThere is no differenceinoutput between the two settings.
- BWith zero reducers, no reducer runs and the job throws an exception. With one reducer,
- CWith zero reducers, all instances of matching patterns are gathered together in one file on
- DWith zero reducers, instances of matching patterns are stored in multiple files on HDFS. With
How the community answered
(43 responses)- A9% (4)
- B5% (2)
- C84% (36)
- D2% (1)
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