{"id":11580,"date":"2018-03-23T09:54:58","date_gmt":"2018-03-23T09:54:58","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=11580"},"modified":"2018-03-23T09:54:58","modified_gmt":"2018-03-23T09:54:58","slug":"apache-hive-interview-questions","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/apache-hive-interview-questions\/","title":{"rendered":"Top 30 Tricky Hive Interview Questions and Answers"},"content":{"rendered":"

While it comes to prepare for a\u00a0Hadoop<\/strong>\u00a0job interview, you should be aware that question may arise on its several tools. Such as\u00a0Flume<\/strong>,\u00a0Sqoop<\/strong>,\u00a0HBase<\/strong>,\u00a0MapReduce<\/strong>,\u00a0Hive<\/strong>\u00a0and many more.<\/p>\n

So, in this blog, ”Hive Interview Questions” we are providing a list of most commonly asked Hive Interview Questions and answers in this year. Hence, that will help you face your Hadoop job interview.<\/p>\n

Basically, to make candidates familiar with the nature of questions that are likely to be asked on the subject of Hive, These Hive scenario based interview questions and answers are formulated.<\/p>\n

Moreover, both freshers, as well as experienced candidates, can refer to this blog. That implies this blog contains questions for every candidate who is preparing for\u00a0a Hadoop job interview<\/strong>.<\/p>\n

\"Hive<\/a>

Most Asked Hive Interview Questions<\/p><\/div>\n

Top 30 Most Asked Interview Questions for\u00a0Hive<\/h2>\n

So, here are top 30 frequently asked Hive Interview Questions:<\/span><\/p>\n

Que 1. What is Apache Hive?<\/b><\/p>\n

Ans.<\/strong>\u00a0Basically, a tool which we call a data warehousing tool is Hive. However, Hive gives SQL queries<\/strong> to perform an analysis and also an abstraction. Although, Hive it is not a database it gives you logical abstraction over the databases and the tables.<\/span><\/p>\n

Que 2. What kind of applications is supported by Apache Hive?<\/b><\/p>\n

Ans.<\/strong>\u00a0All those client applications which are written in\u00a0Java<\/strong>, PHP,\u00a0Python<\/strong>, C++ or Ruby by exposing its thrift server, Hive supports them.<\/span><\/p>\n

Que 3. Is Hive suitable to be used for OLTP systems? Why?<\/b><\/p>\n

Ans.<\/strong>\u00a0No, it is not suitable for OLTP system since it does not offer insert and update at the row level.<\/span><\/p>\n

Que 4. Where does the data of a Hive table gets stored?<\/b><\/p>\n

Ans.<\/strong>\u00a0In an HDFS directory<\/strong> \u2013 \/user\/hive\/warehouse, the Hive table is stored, by default only. Moreover, by specifying the desired directory in hive.metastore.warehouse.dir configuration parameter present in the hive-site.xml, one can change it.\u00a0<\/span>
\n<\/span>
\n<\/span>Que 5. What is a metastore in Hive?<\/b><\/p>\n

Ans<\/strong>. Basically, to store the metadata information in the Hive we use Metastore<\/strong>. Though, it is possible by using RDBMS<\/strong> and an open source ORM (Object Relational Model) layer called Data Nucleus. That converts the object representation into the relational schema and vice versa.<\/span><\/p>\n

Que 6. Why does Hive not store metadata information in HDFS?<\/b><\/p>\n

Ans.<\/strong>\u00a0Using RDBMS instead of HDFS, Hive stores metadata information in the metastore. Basically, to achieve low latency we use RDBMS. Because HDFS read\/write operations<\/strong> are time-consuming processes.<\/span>
\n<\/span>
\n<\/span>Que 7. What is the difference between local and remote metastore?<\/b><\/p>\n

Ans. Local Metastore:<\/strong><\/span><\/p>\n

It is the metastore service runs in the same JVM<\/strong> in which the Hive service is running and connects to a database running in a separate JVM. Either on the same machine or on a remote machine.<\/span>
\n<\/span>
\n<\/span>Remote Metastore:<\/strong>
\n<\/span>
\n<\/span>In this configuration, the metastore service runs on its own separate JVM and not in the Hive service JVM.<\/span>
\n<\/span>
\n<\/span>Que 8. What is the default database provided by Apache Hive for metastore?<\/b><\/p>\n

Ans.<\/strong>\u00a0It offers an embedded Derby database instance backed by the local disk for the metastore, by default. It is what we call embedded metastore configuration.<\/span><\/p>\n

Que 9. What is the difference between the external table and managed table?<\/b><\/p>\n

Ans.\u00a0Managed table<\/strong><\/p>\n

The metadata information along with the table data is deleted from the Hive warehouse directory if one drops a managed table.\\<\/span><\/p>\n

External table<\/strong>
\nHive just deletes the metadata information regarding the table. Further, it leaves the table data present in HDFS untouched.<\/span><\/p>\n

Read more about Hive internal tables vs External tables<\/strong><\/a><\/p>\n

Que 10. Is it possible to change the default location of a managed table?<\/b><\/p>\n

Ans.<\/strong>\u00a0Yes, by using the clause \u2013 LOCATION \u2018<hdfs_path>\u2019 we can change the default location of a managed table.<\/span><\/p>\n

Hive Interview Questions for Freshers- Q. 1,2,3,4,5,7,8,9,10<\/strong><\/p>\n

Hive Interview Questions for Experience- Q. 6<\/strong>
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\n<\/span>Que 11. When should we use SORT BY instead of ORDER BY?<\/b><\/p>\n

A<\/strong><\/span>ns<\/strong>. Despite ORDER BY<\/strong> we should use SORT BY. Especially while we have to sort huge datasets. The reason is SORT BY clause sorts the data using multiple reducers. ORDER BY sorts all of the data together using a single reducer. <\/span><\/p>\n

Hence, using ORDER BY will take a lot of time to execute a large number of inputs.<\/span><\/p>\n

Que 12. What is a partition in Hive?<\/b><\/p>\n

Ans.<\/strong>\u00a0Basically, for the purpose of grouping similar type of data together on the basis of column or partition key, Hive organizes tables into partitions. <\/span><\/p>\n

Moreover, to identify a particular partition each table can have one or more partition keys. On defining Hive Partition<\/strong>, in other words, it is a sub-directory in the table directory.<\/span><\/p>\n

Que 13. Why do we perform partitioning in Hive?<\/b><\/p>\n

Ans.<\/strong>\u00a0In a Hive table, Partitioning provides granularity. Hence, by scanning only relevant partitioned data instead of the whole dataset it reduces the query latency.<\/span>
\n<\/span>
\n<\/span>Que 14. What is dynamic partitioning and when is it used?<\/b><\/p>\n

Ans.<\/strong>\u00a0Dynamic partitioning values for partition columns are known in the runtime. In other words, it is known during loading of the data into a Hive table.<\/span><\/p>\n