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The Ultimate Cheat Sheet On Hadoop

Top 20 frequently asked questions to test your Hadoop knowledge given in the below Hadoop cheat sheet. Try finding your own answers and match the answers given here.




Question #1 

You have written a MapReduce job that will process 500 million input records and generate 500 million key-value pairs. The data is not uniformly distributed. Your MapReduce job will create a significant amount of intermediate data that it needs to transfer between mappers and reducers which is a potential bottleneck. A custom implementation of which of the following interfaces is most likely to reduce the amount of intermediate data transferred across the network?



A. Writable
B. WritableComparable
C. InputFormat
D. OutputFormat
E. Combiner
F. Partitioner
Ans: e




Question #2 

Where is Hive metastore stored by default ?


A. In HDFS
B. In client machine in the form of a flat file.
C. In client machine in a derby database
D. In lib directory of HADOOP_HOME, and requires HADOOP_CLASSPATH to be modified.
Ans: c




Question…

Big Data: Top NoSQL Interview Questions (2 of 5)

Oracle+NoSQL+JOBS
1) What is most important character of NoSQL?
High Availability

2)Different types of NoSQL databases?
Key-Value stores
Column Stores
Graph Stores
Document Stores

3)What is oracle NoSQL database?
Oracle NoSQL Database is a distributed key-value database designed to provide highly reliable, scalable, and available data storage across a configurable set of systems.

4)What is the DB engine being used in Oracle NoSQL database?
Oracle NoSQL Database uses Oracle Berkeley DB Java Edition as the underlying data storage engine.

5)What is oracle NoSQL database?
Oracle NoSQL Database is a shared-nothing system designed to run and scale on commodity hardware. Key-value pairs are hash partitioned across server groups known as shards. At any point in time, a single key-value pair is always associated with a unique shard in the system.

6) What are unique features of Oracle NoSQL?
Oracle NoSQL Database leverages the high availability features in Berkeley DB in order to provide resiliency, fault tolerance, and read scalability.

7)What is the concept of shared nothing in Oracle NoSQL database?
A shared-nothing system partitions the data into disjoint subsets (called shards), each shard managed by a node (along with replicas for providing high availability).

8) How oracle NoSQL acheives high availablity?
Availability is achieved by adding redundancy to the system. In NoSQL systems, redundancy is commonly achieved by maintaining multiple copies of the data on multiple nodes. Each shard comprises two or more nodes (called replicas) that have identical copies of the data.

9) What is ACID in Oracle NoSQL?
Atomicity, consistency, isolation, and durability (ACID) are the key characteristics provided by transactions. Oracle NoSQL Database leverages the transaction capabilities of the underlying Berkeley DB storage engine.

10)How data will be modeled in No SQL Database?
Oracle NoSQL Database provides a key-value paradigm to the application developer. Every entity (record) is a set of key-value pairs. A key has multiple components, specified as an ordered list. The major key identifies the entity and consists of the leading components of the key. The subsequent components are called minor keys.
This organization is similar to a directory path specification in a file system (for example, /Major/minor1/minor2/). The "value" part of the key-value pair is simply an uninterpreted string of bytes of arbitrary length.

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