Cloudera Certified Developer for Apache Hadoop (CCDH) 認定 CCD-410 試験問題:

1. Which best describes how TextInputFormat processes input files and line breaks?

A) Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReader of the split that contains the end of the broken line.
B) Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReader of the split that contains the beginning of the broken line.
C) Input file splits may cross line breaks. A line that crosses file splits is ignored.
D) Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReaders of both splits containing the broken line.
E) The input file is split exactly at the line breaks, so each RecordReader will read a series of complete lines.

2. When can a reduce class also serve as a combiner without affecting the output of a MapReduce program?

A) When the signature of the reduce method matches the signature of the combine method.
B) Never. Combiners and reducers must be implemented separately because they serve different purposes.
C) Always. The point of a combiner is to serve as a mini-reducer directly after the map phase to increase performance.
D) When the types of the reduce operation's input key and input value match the types of the reducer's output key and output value and when the reduce operation is both communicative and associative.
E) Always. Code can be reused in Java since it is a polymorphic object-oriented programming language.

3. Indentify which best defines a SequenceFile?

A) A SequenceFile contains a binary encoding of an arbitrary number of homogeneous Writable objects
B) A SequenceFile contains a binary encoding of an arbitrary number of heterogeneous Writable objects
C) A SequenceFile contains a binary encoding of an arbitrary number of WritableComparable objects, in sorted order.
D) A SequenceFile contains a binary encoding of an arbitrary number key-value pairs. Each key must be the same type. Each value must be the same type.

4. In a MapReduce job, the reducer receives all values associated with same key. Which statement best describes the ordering of these values?

A) The values are arbitrary ordered, but multiple runs of the same MapReduce job will always have the same ordering.
B) Since the values come from mapper outputs, the reducers will receive contiguous sections of sorted values.
C) The values are in sorted order.
D) The values are arbitrarily ordered, and the ordering may vary from run to run of the same MapReduce job.

5. Analyze each scenario below and indentify which best describes the behavior of the default partitioner?

A) The default partitioner computes the hash of the key. Hash values between specific ranges are associated with different buckets, and each bucket is assigned to a specific reducer.
B) The default partitioner implements a round-robin strategy, shuffling the key-value pairs to each reducer in turn. This ensures an event partition of the key space.
C) The default partitioner computes the hash of the value and takes the mod of that value with the number of reducers. The result determines the reducer assigned to process the key-value pair.
D) The default partitioner assigns key-values pairs to reduces based on an internal random number generator.
E) The default partitioner computes the hash of the key and divides that valule modulo the number of reducers. The result determines the reducer assigned to process the key-value pair.

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