Engineering Questions with Answers - Multiple Choice Questions
MCQs on User-defined Functions in Pig
1 - Question
__________ abstract class has three main methods for loading data and for most use cases it would suffice to extend it.
a) Load
b) LoadFunc
c) FuncLoad
d) None of the mentioned
View Answer
Answer: b
Explanation: LoadFunc and StoreFunc implementations should use the Hadoop 20 API based classes.
2 - Question
Point out the correct statement.
a) LoadMeta has methods to convert byte arrays to specific types
b) The Pig load/store API is aligned with Hadoop InputFormat class only
c) LoadPush has methods to push operations from Pig runtime into loader implementations
d) All of the mentioned
View Answer
Answer: c
Explanation: Currently only the pushProjection() method is called by Pig to communicate to the loader the exact fields that are required in the Pig script.
3 - Question
Which of the following has methods to deal with metadata?
a) LoadPushDown
b) LoadMetadata
c) LoadCaster
d) All of the mentioned
View Answer
Answer: b
Explanation: Most implementation of loaders don’t need to implement this unless they interact with some metadata system.
4 - Question
____________ method will be called by Pig both in the front end and back end to pass a unique signature to the Loader.
a) relativeToAbsolutePath()
b) setUdfContextSignature()
c) getCacheFiles()
d) getShipFiles()
View Answer
Answer: b
Explanation: The signature can be used to store into the UDFContext any information which the Loader needs to store between various method invocations in the front end and back end.
5 - Question
Point out the wrong statement.
a) The load/store UDFs control how data goes into Pig and comes out of Pig.
b) LoadCaster has methods to convert byte arrays to specific types.
c) The meaning of getNext() has changed and is called by Pig runtime to get the last tuple in the data
d) None of the mentioned
View Answer
Answer: c
Explanation: The meaning of getNext() has not changed and is called by Pig runtime to get the next tuple in the data.
Explanation: The meaning of getNext() has not changed and is called by Pig runtime to get the next tuple in the data.
6 - Question
___________ return a list of hdfs files to ship to distributed cache.
a) relativeToAbsolutePath()
b) setUdfContextSignature()
c) getCacheFiles()
d) getShipFiles()
View Answer
Answer: d
Explanation: The default implementation provided in LoadFunc handles this for FileSystem locations.
7 - Question
The loader should use ______ method to communicate the load information to the underlying InputFormat.
a) relativeToAbsolutePath()
b) setUdfContextSignature()
c) getCacheFiles()
d) setLocation()
View Answer
Answer: d
Explanation: setLocation() method is called by Pig to communicate the load location to the loader.
8 - Question
____________ method enables the RecordReader associated with the InputFormat provided by the LoadFunc is passed to the LoadFunc.
a) getNext()
b) relativeToAbsolutePath()
c) prepareToRead()
d) all of the mentioned
View Answer
Answer: c
Explanation: The RecordReader can then be used by the implementation in getNext() to return a tuple representing a record of data back to pig.
9 - Question
__________ method tells LoadFunc which fields are required in the Pig script.
a) pushProjection()
b) relativeToAbsolutePath()
c) prepareToRead()
d) none of the mentioned
View Answer
Answer: a
Explanation: Pig will use the column index requiredField.index to communicate with the LoadFunc about the fields required by the Pig script.
10 - Question
A loader implementation should implement __________ if casts (implicit or explicit) from DataByteArray fields to other types need to be supported.
a) LoadPushDown
b) LoadMetadata
c) LoadCaster
d) All of the mentioned
View Answer
Answer: c
Explanation: LoadCaster has methods to convert byte arrays to specific types.