Max (in value) of columns (in a single row) in Hive

Question

How do I get max value from different columns from a row in HIVE?

For instance

Row# ID# Col1 Col2 Col3
1    1234  54  67  86
2    5678  89   92 86
...
...

Looking for output of the form:

1234 86
5678 92

Thanks!

Answer 1

Hive has the greatest() function as of 1.1;

select ID, greatest(col1, col2, col3) as greatest_value from table;

Or you can use a case when statement if your version doesn't have greatest():

select ID
, case
   when col1 >  col2 and col1 >  col3 then col1
   when col2 >  col3                  then col2
   else                                    col3
  end as greatest_value
from  table
;

Case when statements are evaluated in order from top to bottom until a value of true is found, so no need to evaluate two inequalities in each when clause.