Hive Interview Questions and Answers

 

1) Explain about the SMB Join in Hive.

In SMB join in Hive, each mapper reads a bucket from the first table and the corresponding bucket from the second table and then a merge sort join is performed. Sort Merge Bucket (SMB) join in hive is mainly used as there is no limit on file or partition or table join. SMB join can best be used when the tables are large. In SMB join the columns are bucketed and sorted using the join columns. All tables should have the same number of buckets in SMB join.

2) How can you connect an application, if you run Hive as a server?

When running Hive as a server, the application can be connected in one of the 3 ways-

ODBC Driver-This supports the ODBC protocol

JDBC Driver- This supports the JDBC protocol

Thrift Client- This client can be used to make calls to all hive commands using different programming language like PHP, Python, Java, C++ and Ruby.

3) What does the overwrite keyword denote in Hive load statement?

Overwrite keyword in Hive load statement deletes the contents of the target table and replaces them with the files referred by the file path i.e. the files that are referred by the file path will be added to the table when using the overwrite keyword.

4) What is SerDe in Hive? How can you write your own custom SerDe?

SerDe is a Serializer DeSerializer. Hive uses SerDe to read and write data from tables. Generally, users prefer to write a Deserializer instead of a SerDe as they want to read their own data format rather than writing to it. If the SerDe supports DDL i.e. basically SerDe with parameterized columns and different column types, the users can implement a Protocol based DynamicSerDe rather than writing the SerDe from scratch.

We have further categorized Hadoop Hive Interview Questions for Freshers and Experienced-

Hadoop Hive Interview Questions and Answers for Freshers- Q.Nos-3

Hadoop Hive Interview Questions and Answers for Experienced- Q.Nos-1,2,4

Here are a few more frequently asked  Hadoop Hive Interview Questions and Answers for Freshers and Experienced