Hadoop

Questions and Answers

• Partitioner controls the partitioning of what data?
  1. final keys
  2. final values
  3. intermediate keys
  4. intermediate values
• SQL Windowing functions are implemented in Hive using which keywords?
  1. UNION DISTINCT, RANK
  2. OVER, RANK
  3. OVER, EXCEPT
  4. UNION DISTINCT, RANK
• Rather than adding a Secondary Sort to a slow Reduce job, it is Hadoop best practice to perform which optimization?
  1. Add a partitioned shuffle to the Map job.
  2. Add a partitioned shuffle to the Reduce job.
  3. Break the Reduce job into multiple, chained Reduce jobs.
  4. Break the Reduce job into multiple, chained Map jobs.
• Hadoop Auth enforces authentication on protected resources. Once authentication has been established, it sets what type of authenticating cookie?
  1. encrypted HTTP
  2. unsigned HTTP
  3. compressed HTTP
  4. signed HTTP
• MapReduce jobs can be written in which language?
  1. Java or Python
  2. SQL only
  3. SQL or Java
  4. Python or SQL
• To perform local aggregation of the intermediate outputs, MapReduce users can optionally specify which object?
  1. Reducer
  2. Combiner
  3. Mapper
  4. Counter
• To verify job status, look for the value `___` in the `___`.
  1. SUCCEEDED; syslog
  2. SUCCEEDED; stdout
  3. DONE; syslog
  4. DONE; stdout
• Which line of code implements a Reducer method in MapReduce 2.0?
  1. public void reduce(Text key, Iterator values, Context context){?}
  2. public static void reduce(Text key, IntWritable[] values, Context context){?}
  3. public static void reduce(Text key, Iterator values, Context context){?}
  4. public void reduce(Text key, IntWritable[] values, Context context){?}
• To get the total number of mapped input records in a map job task, you should review the value of which counter?
  1. FileInputFormatCounter
  2. FileSystemCounter
  3. JobCounter
  4. TaskCounter (NOT SURE)
• Hadoop Core supports which CAP capabilities?
  1. A, P
  2. C, A
  3. C, P
  4. C, A, P
• What are the primary phases of a Reducer?
  1. combine, map, and reduce
  2. shuffle, sort, and reduce
  3. reduce, sort, and combine
  4. map, sort, and combine
• To set up Hadoop workflow with synchronization of data between jobs that process tasks both on disk and in memory, use the `___` service, which is `___`.
  1. Oozie; open source
  2. Oozie; commercial software
  3. Zookeeper; commercial software
  4. Zookeeper; open source
• For high availability, use multiple nodes of which type?
  1. data
  2. name
  3. memory
  4. worker
• DataNode supports which type of drives?
  1. hot swappable
  2. cold swappable
  3. warm swappable
  4. non-swappable
• Which method is used to implement Spark jobs?
  1. on disk of all workers
  2. on disk of the master node
  3. in memory of the master node
  4. in memory of all workers
• In a MapReduce job, where does the map() function run?
  1. on the reducer nodes of the cluster
  2. on the data nodes of the cluster (NOT SURE)
  3. on the master node of the cluster
  4. on every node of the cluster
• To reference a master file for lookups during Mapping, what type of cache should be used?
  1. distributed cache
  2. local cache
  3. partitioned cache
  4. cluster cache
• Skip bad records provides an option where a certain set of bad input records can be skipped when processing what type of data?
  1. cache inputs
  2. reducer inputs
  3. intermediate values
  4. map inputs
• Which command imports data to Hadoop from a MySQL database?
  1. spark import --connect jdbc:mysql://mysql.example.com/spark --username spark --warehouse-dir user/hue/oozie/deployments/spark
  2. sqoop import --connect jdbc:mysql://mysql.example.com/sqoop --username sqoop --warehouse-dir user/hue/oozie/deployments/sqoop
  3. sqoop import --connect jdbc:mysql://mysql.example.com/sqoop --username sqoop --password sqoop --warehouse-dir user/hue/oozie/deployments/sqoop
  4. spark import --connect jdbc:mysql://mysql.example.com/spark --username spark --password spark --warehouse-dir user/hue/oozie/deployments/spark
• In what form is Reducer output presented?
  1. compressed (NOT SURE)
  2. sorted
  3. not sorted
  4. encrypted
• Which library should be used to unit test MapReduce code?
  1. JUnit
  2. XUnit
  3. MRUnit
  4. HadoopUnit
• If you started the NameNode, then which kind of user must you be?
  1. hadoop-user
  2. super-user
  3. node-user
  4. admin-user
• State \_ between the JVMs in a MapReduce job
  1. can be configured to be shared
  2. is partially shared
  3. is shared
  4. is not shared (https://www.lynda.com/Hadoop-tutorials/Understanding-Java-virtual-machines-JVMs/191942/369545-4.html)
• To create a MapReduce job, what should be coded first?
  1. a static job() method
  2. a Job class and instance (NOT SURE)
  3. a job() method
  4. a static Job class
• To connect Hadoop to AWS S3, which client should you use?
  1. S3A
  2. S3N
  3. S3
  4. the EMR S3
• HBase works with which type of schema enforcement?
  1. schema on write
  2. no schema
  3. external schema
  4. schema on read
• HDFS file are of what type?
  1. read-write
  2. read-only
  3. write-only
  4. append-only
• A distributed cache file path can originate from what location?
  1. hdfs or top
  2. http
  3. hdfs or http
  4. hdfs
• Which library should you use to perform ETL-type MapReduce jobs?
  1. Hive
  2. Pig
  3. Impala
  4. Mahout
• What is the output of the Reducer?
  1. a relational table
  2. an update to the input file
  3. a single, combined list
  4. a set of pairs
• To optimize a Mapper, what should you perform first?
  1. Override the default Partitioner.
  2. Skip bad records.
  3. Break up Mappers that do more than one task into multiple Mappers.
  4. Combine Mappers that do one task into large Mappers.
• When implemented on a public cloud, with what does Hadoop processing interact?
  1. files in object storage
  2. graph data in graph databases
  3. relational data in managed RDBMS systems
  4. JSON data in NoSQL databases
• In the Hadoop system, what administrative mode is used for maintenance?
  1. data mode
  2. safe mode
  3. single-user mode
  4. pseudo-distributed mode
• In what format does RecordWriter write an output file?
  1. pairs
  2. keys
  3. values
  4. pairs
• To what does the Mapper map input key/value pairs?
  1. an average of keys for values
  2. a sum of keys for values
  3. a set of intermediate key/value pairs
  4. a set of final key/value pairs
• Which Hive query returns the first 1,000 values?
  1. SELECT?WHERE value = 1000
  2. SELECT ? LIMIT 1000
  3. SELECT TOP 1000 ?
  4. SELECT MAX 1000?
• To implement high availability, how many instances of the master node should you configure?
  1. one
  2. zero
  3. shared
  4. two or more (https://data-flair.training/blogs/hadoop-high-availability-tutorial)
• Hadoop 2.x and later implement which service as the resource coordinator?
  1. kubernetes
  2. JobManager
  3. JobTracker
  4. YARN
• In MapReduce, **\_** have \_
  1. tasks; jobs
  2. jobs; activities
  3. jobs; tasks
  4. activities; tasks
• What type of software is Hadoop Common?
  1. database
  2. distributed computing framework
  3. operating system
  4. productivity tool
• If no reduction is desired, you should set the numbers of \_ tasks to zero
  1. combiner
  2. reduce
  3. mapper
  4. intermediate
• MapReduce applications use which of these classes to report their statistics?
  1. mapper
  2. reducer
  3. combiner
  4. counter
• \_ is the query language, and \_ is storage for NoSQL on Hadoop
  1. HDFS; HQL
  2. HQL; HBase
  3. HDFS; SQL
  4. SQL; HBase
• MapReduce 1.0 \_ YARN
  1. does not include
  2. is the same thing as
  3. includes
  4. replaces
• Which type of Hadoop node executes file system namespace operations like opening, closing, and renaming files and directories?
  1. ControllerNode
  2. DataNode
  3. MetadataNode
  4. NameNode
• HQL queries produce which job types?
  1. Impala
  2. MapReduce
  3. Spark
  4. Pig
• Suppose you are trying to finish a Pig script that converts text in the input string to uppercase. What code is needed on line 2 below?
  1. as (text:CHAR[]); upper_case = FOREACH data GENERATE org.apache.pig.piggybank.evaluation.string.UPPER(TEXT);
  2. as (text:CHARARRAY); upper_case = FOREACH data GENERATE org.apache.pig.piggybank.evaluation.string.UPPER(TEXT);
  3. as (text:CHAR[]); upper_case = FOREACH data org.apache.pig.piggybank.evaluation.string.UPPER(TEXT);
  4. as (text:CHARARRAY); upper_case = FOREACH data org.apache.pig.piggybank.evaluation.string.UPPER(TEXT);
• In a MapReduce job, which phase runs after the Map phase completes?
  1. Combiner
  2. Reducer
  3. Map2
  4. Shuffle and Sort
• Where would you configure the size of a block in a Hadoop environment?
  1. dfs.block.size in hdfs-site.xmls
  2. orc.write.variable.length.blocks in hive-default.xml
  3. mapreduce.job.ubertask.maxbytes in mapred-site.xml
  4. hdfs.block.size in hdfs-site.xml
• Hadoop systems are **\_** RDBMS systems.
  1. replacements for
  2. not used with
  3. substitutes for
  4. additions for
• Which object can be used to distribute jars or libraries for use in MapReduce tasks?
  1. distributed cache
  2. library manager
  3. lookup store
  4. registry
• To view the execution details of an Impala query plan, which function would you use ?
  1. explain
  2. query action
  3. detail
  4. query plan
• Which feature is used to roll back a corrupted HDFS instance to a previously known good point in time?
  1. partitioning
  2. snapshot
  3. replication
  4. high availability
• Hadoop Common is written in which language?
  1. C++
  2. C
  3. Haskell
  4. Java
• Which file system does Hadoop use for storage?
  1. NAS
  2. FAT
  3. HDFS
  4. NFS
• What kind of storage and processing does Hadoop support?
  1. encrypted
  2. verified
  3. distributed
  4. remote
• Hadoop Common consists of which components?
  1. Spark and YARN
  2. HDFS and MapReduce
  3. HDFS and S3
  4. Spark and MapReduce
• Most Apache Hadoop committers' work is done at which commercial company?
  1. Cloudera
  2. Microsoft
  3. Google
  4. Amazon
• To get information about Reducer job runs, which object should be added?
  1. Reporter
  2. IntReadable
  3. IntWritable
  4. Writer
• After changing the default block size and restarting the cluster, to which data does the new size apply?
  1. all data
  2. no data
  3. existing data
  4. new data
• Which statement should you add to improve the performance of the following query?
  1. GROUP BY
  2. FILTER
  3. SUB-SELECT
  4. SORT
• What custom object should you implement to reduce IO in MapReduce?
  1. Comparator
  2. Mapper
  3. Combiner
  4. Reducer
• You can optimize Hive queries using which method?
  1. secondary indices
  2. summary statistics
  3. column-based statistics
  4. a primary key index
• If you are processing a single action on each input, what type of job should you create?
  1. partition-only
  2. map-only
  3. reduce-only
  4. combine-only
• The simplest possible MapReduce job optimization is to perform which of these actions?
  1. Add more master nodes.
  2. Implement optimized InputSplits.
  3. Add more DataNodes.
  4. Implement a custom Mapper.
• When you implement a custom Writable, you must also define which of these object?
  1. a sort policy
  2. a combiner policy
  3. a compression policy
  4. a filter policy
• To copy a file into the Hadoop file system, what command should you use?
  1. hadoop fs -copy
  2. hadoop fs -copy
  3. hadoop fs -copyFromLocal
  4. hadoop fs -copyFromLocal