Big Data Online Practice Test - 8

Q. A developer was studying,about the Safe mode, of Hadoop system:
1) In safe mode,the namenode never allows,any replication. Though deletion of blocks,is allowed.
2) The namenode leaves the safe mode,once,the datanodes report,that many of the blocks,are accessible.
3) On startup of the cluster, the developer or admin,should mention that,namenode should enter,the safe mode.
4) Whenever,a certain percentage,of blocks unavailability, is reached, HDFS enters safe mode.
Mark the correct option.

Q. In a quiz competition, following statement was given:
Find documents,from the Travel collection,where the country name,has a 'z' at any position.
Mark the correct syntax.

Q. Freshers were learning,about Java and Scala. Below,are a few features,mentioned. Mark which of them,is of Java or Scala:
1) This framework,slows up complex computation,and,performs them,only if necessary.
2) Here, the compilation of source code,to bytecode,takes a lot of time.
3) The programming language,is more readable.
4) This language,trusts in,Read Evaluate Print Loop(REPL).
Mark the correct option

Q. A developer was running some queries in Pig. He wanted to get,first 4 rows,from the "ports" relation
Mark the correct syntax.

Q. A fresher was given,the following question,in a technical test.What happens,when following changes,are done to a Hive table:
1) A managed table is dropped.
2) A table is partitioned.
Mark the correct option.

Q. A developer was working on some code snippets in Scala:

 
#1
scala>def egfnc1()={ return 12 }

#2
scala> def egfnc2(x:Int=2,y:String){
     println(s"$x $y")
     }

Mark the correct output,for the snippets.

Q. In a quiz,developers were told to identify,the valid or invalid remarks,about Hadoop counters:
1) To determine,the number of operations,within the mapreduce job,counters come in handy.
2) Every Hadoop counter,is named by an Enum, and, has a double for a value.
3) Counters help to validate,the number of bytes that are read and written.But it cannot give, the total tasks,launched.
4) A custom or a user-defined counter,can be written, on the mapper side,but not on the reducer side.
Mark the correct option.

Q. A technical writer, was told to write an article,on the sorting algorithm,used in Mapreduce.
Which of the following statements are correct/incorrect:
1) On the reducer side, merge sort is used for sorting.
2) One can change,the Mapreduce sorting method,by mentioning the Job.setSortMethod(method name)
3) One can mention, the comparator class too,by setting the Job.setSortComparator(Classname).
4) The default feature, of mapreduce,is the Merge sort.
Mark the appropriate option.

Q. A developer,was told to find,the number of mappers,in the following scenario.
File size is 300Mb.Block size is 128Mb.
1) Split size is 100Mb
2) Split size is 128Mb
3) Split size is 200Mb
Mark the correct option.

Q. A developer was working on a complex mapreduce job.He was told, to run,two parallel jobs. Below are a few descriptive statements regarding the same:
1) Hadoop has a default scheduler,which is the, FIFO scheduler.
2) If the map task capacity,of a cluster, is 10,and suppose, jobnumber1 requires 5 map task, and jobnumber2 needs 5 map task. Then too, jobnumber2 runs,after jobnumber1 is finished.
3) The job.submit() method can be used easily,when, jobs are running in parallel.
4) To configure a scheduler, one can set the option in mapred-site.xml.
Mark the correct option.