Hadoop Hive MCQ Questions and Answers

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1. What is Apache Hive primarily used for?

a) Real-time processing
b) Data storage
c) Data warehousing
d) Network configuration

Answer:

c) Data warehousing

Explanation:

Apache Hive is a data warehousing solution built on top of Hadoop, used for querying and managing large datasets residing in distributed storage.

2. Which language is used to write Hive queries?

a) Java
b) Python
c) HiveQL
d) SQL

Answer:

c) HiveQL

Explanation:

Hive queries are written in HiveQL, a SQL-like language that allows traditional map/reduce programmers to query the data without any knowledge of Java.

3. What is the function of the Metastore in Hive?

a) Storing the actual data
b) Managing user permissions
c) Storing metadata about tables and partitions
d) Executing Hive queries

Answer:

c) Storing metadata about tables and partitions

Explanation:

The Metastore in Hive is a critical component that stores metadata about the structure of tables, their columns and datatypes, and the data's physical location.

4. Hive Tables are divided into which two main categories?

a) Local and External tables
b) Managed and External tables
c) Static and Dynamic tables
d) Temporary and Permanent tables

Answer:

b) Managed and External tables

Explanation:

In Hive, tables are categorized into Managed (internal) tables, where Hive manages the data lifecycle, and External tables, where data is managed outside of Hive.

5. Which file format is not natively supported by Hive?

a) ORC
b) Parquet
c) CSV
d) JSON

Answer:

d) JSON

Explanation:

While Hive natively supports ORC, Parquet, and CSV formats, JSON is not natively supported but can be used with custom SerDe (Serializer/Deserializer).

6. What does 'PARTITIONED BY' clause do in Hive?

a) Sorts data within a table
b) Merges two tables
c) Divides a table into smaller, manageable parts
d) Filters data in a query

Answer:

c) Divides a table into smaller, manageable parts

Explanation:

The 'PARTITIONED BY' clause in Hive is used to divide a table into smaller, more manageable parts, each of which can be stored and queried separately.

7. What type of query system does Hive use?

a) OLTP (Online Transaction Processing)
b) OLAP (Online Analytical Processing)
c) Real-Time Processing
d) Batch Processing

Answer:

b) OLAP (Online Analytical Processing)

Explanation:

Hive is designed for OLAP and is suitable for data warehousing applications where queries are complex and involve a large amount of data.

8. Which Hive component is responsible for compiling, optimizing, and executing queries?

a) Metastore
b) Driver
c) Compiler
d) Executor

Answer:

b) Driver

Explanation:

The Driver in Hive is responsible for receiving the queries, compiling them, optimizing the execution plan, and executing the queries on the Hadoop cluster.

9. In Hive, what is a SerDe?

a) A type of database
b) A query optimization tool
c) Serializer and Deserializer
d) A data storage format

Answer:

c) Serializer and Deserializer

Explanation:

A SerDe (Serializer/Deserializer) in Hive is responsible for defining how to translate a data object into and from Hadoop's storage formats (like SequenceFile, Avro, ORC).

10. What is the purpose of Hive's 'EXPLAIN' command?

a) To create a new database
b) To export data from a table
c) To display the execution plan of a query
d) To change the data type of a column

Answer:

c) To display the execution plan of a query

Explanation:

The 'EXPLAIN' command in Hive is used to display the execution plan for a query, showing how the query will be transformed into a series of MapReduce jobs.

11. What is an 'External Table' in Hive?

a) A table that links to an external database
b) A temporary table for query results
c) A table that stores its data outside of Hive
d) A table that can only be queried externally

Answer:

c) A table that stores its data outside of Hive

Explanation:

An External Table in Hive is a table where the data is stored outside of Hive, meaning that Hive does not manage or modify the data itself.

12. Which type of join does Hive not natively support?

a) Inner join
b) Left outer join
c) Right outer join
d) Full outer join

Answer:

d) Full outer join

Explanation:

As of the traditional versions of Hive, it does not natively support full outer joins. However, inner and left/right outer joins are supported.

13. What is the default file format for Hive?

a) TextFile
b) ORC
c) Parquet
d) Avro

Answer:

a) TextFile

Explanation:

The default file format for Hive is TextFile, which is human-readable and easy to use but not the most efficient in terms of storage and performance.

14. Which Hive command is used to add a new column to a table?

a) ALTER TABLE … ADD COLUMN
b) MODIFY TABLE … ADD COLUMN
c) UPDATE TABLE … ADD COLUMN
d) CHANGE TABLE … ADD COLUMN

Answer:

a) ALTER TABLE … ADD COLUMN

Explanation:

The 'ALTER TABLE … ADD COLUMN' command in Hive is used to add a new column to an existing table.

15. How does Hive process queries?

a) By executing them in real-time
b) By translating them into SQL
c) By converting them into MapReduce jobs
d) By processing them through a traditional RDBMS

Answer:

c) By converting them into MapReduce jobs

Explanation:

Hive processes queries by translating HiveQL into MapReduce jobs, which are then executed on the Hadoop cluster.

16. What is Bucketing in Hive?

a) Splitting data into multiple files based on a hash function
b) Creating multiple partitions for a table
c) Storing data in compressed format
d) Encrypting data stored in Hive tables

Answer:

a) Splitting data into multiple files based on a hash function

Explanation:

Bucketing in Hive involves splitting data into a manageable and more efficiently processed form, where data is stored in buckets based on a hash function of a column.

17. What is the purpose of the 'HAVING' clause in Hive?

a) To specify conditions for groupings
b) To filter individual rows
c) To join multiple tables
d) To sort the result set

Answer:

a) To specify conditions for groupings

Explanation:

The 'HAVING' clause in Hive is used to specify conditions on the groups formed by the 'GROUP BY' clause, similar to its use in SQL.

18. Which Hive command is used for removing a database?

a) DROP DATABASE
b) REMOVE DATABASE
c) DELETE DATABASE
d) ERASE DATABASE

Answer:

a) DROP DATABASE

Explanation:

The 'DROP DATABASE' command in Hive is used to delete a database and optionally all of its tables.

19. What is the 'LOAD DATA' command used for in Hive?

a) Loading data into a Hive table from HDFS
b) Exporting data from a Hive table to HDFS
c) Loading a UDF into Hive
d) Data transformation within Hive tables

Answer:

a) Loading data into a Hive table from HDFS

Explanation:

The 'LOAD DATA' command in Hive is used to load data into a table from a file or directory in HDFS or local file system.

20. How does Hive handle updates and deletions on tables?

a) It supports real-time updates and deletions
b) It does not support updates and deletions by default
c) It uses SQL triggers for updates and deletions
d) It automatically updates and deletes data based on queries

Answer:

b) It does not support updates and deletions by default

Explanation:

Traditional versions of Hive do not support updates and deletions on tables by default, as it is primarily designed for appending and reading large datasets.

21. What is the role of the 'ORDER BY' clause in Hive?

a) To create an ordered list of table columns
b) To sort the output of a query in ascending or descending order
c) To order the execution of multiple queries
d) To arrange the partitions in a specific order

Answer:

b) To sort the output of a query in ascending or descending order

Explanation:

The 'ORDER BY' clause in Hive is used to sort the results of a query in either ascending or descending order based on one or more columns.

22. Which Hive feature allows the use of custom mappers and reducers?

a) UDFs (User Defined Functions)
b) Custom scripts
c) Transform clauses
d) Plugins

Answer:

c) Transform clauses

Explanation:

Hive's Transform clauses allow the use of custom mappers and reducers for processing data, enabling integration of custom scripts and processing logic.

23. How is data stored in a Hive table that uses the ORC file format?

a) As plain text
b) In a columnar format
c) In a key-value pair format
d) In a graph-based format

Answer:

b) In a columnar format

Explanation:

The ORC (Optimized Row Columnar) file format is a highly efficient columnar storage format used by Hive, providing significant improvements in performance and storage efficiency.

24. What is the use of the 'LIMIT' keyword in Hive queries?

a) To restrict the number of rows returned by a query
b) To set a time limit for query execution
c) To limit the number of mappers and reducers
d) To define the maximum size of the result set

Answer:

a) To restrict the number of rows returned by a query

Explanation:

The 'LIMIT' keyword in Hive is used to restrict the query results to a specified number of rows, which is useful for testing queries or when only a subset of the data is needed.

25. What is the purpose of the 'INSERT OVERWRITE' statement in Hive?

a) To append data to a table
b) To update existing data in a table
c) To overwrite existing data in a table or partition
d) To insert new columns into a table

Answer:

c) To overwrite existing data in a table or partition

Explanation:

The 'INSERT OVERWRITE' statement in Hive is used to overwrite the existing data in a table or partition with new data, effectively replacing the current data with new data specified in the query.

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