Hive interview questions part-5

 What are the default record and field delimiter used for hive text files?

The default record delimiter is − \n

And the filed delimiters are − \001,\002,\003

What do you mean by schema on read?

The schema is validated with the data when reading the data and not enforced when writing data.

How do you list all databases whose name starts with p?

SHOW DATABASES LIKE ‘p.*’

What does the “USE” command in hive do?

With the use command you fix the database on which all the subsequent hive queries will run.

How can you delete the DBPROPERTY in Hive?

There is no way you can delete the DBPROPERTY.

What is the significance of the line

set hive.mapred.mode = strict;

It sets the mapreduce jobs to strict mode.By which the queries on partitioned tables can not run without a WHERE clause. This prevents very large job running for long time.

How do you check if a particular partition exists?

This can be done with following query

SHOW PARTITIONS table_name PARTITION(partitioned_column=’partition_value’)

Which java class handles the Input record encoding into files which store the tables in Hive?

org.apache.hadoop.mapred.TextInputFormat

Which java class handles the output record encoding into files which result from Hive queries?

org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat

What is the significance of ‘IF EXISTS” clause while dropping a table?

When we issue the command DROP TABLE IF EXISTS table_name

Hive throws an error if the table being dropped does not exist in the first place.