36. 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.
USE sets the current database for all subsequent HiveQL statements. To revert to the default database, use the keyword “default” instead of a database name.
37. How can you delete the DBPROPERTY in Hive ?
There is no way you can delete the DBPROPERTY.
38. 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.
39. 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’)
40. Which java class handles the Input record encoding into files which store the tables in Hive ?
41. Which java class handles the output record encoding into files which result from Hive queries ?
42. 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
hive> DROP DATABASE IF EXISTS financials;
The IF EXISTS is optional and suppresses warnings if financials doesn’t exist.