Handling null values on hive
In Hive, count(*) counts all rows and count(columnA) will only count rows where columnA is non-NULL. If you would like to do multiple columns you could write the query as:
select count(*)-count(columnA), count(*)-count(columnB) from table;and get the number of null values in each column. https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF