我不确定这在Hive里能不能用。我知道它和sql非常相似。试试看。

select item, year,
'Jan' as Month,
Jan as value
from yourtable
UNION
select item, year,
'Feb' as Month,
Feb as value
from yourtable
UNION
select item, year,
'Mar' as Month,
Mar as value
from yourtable

@vkp让我朝着正确的方向开始，但我不得不添加一些调整，使它在hive上工作：

CREATE TABLE myDatabase.newTable STORED AS TEXTFILE AS 
SELECT item, year, 'jan' AS Month, jan AS Value FROM myDatabase.myTable UNION ALL
SELECT item, year, 'feb' AS Month, feb AS Value FROM myDatabase.myTable UNION ALL
SELECT item, year, 'mar' AS Month, mar AS Value FROM myDatabase.myTable;

仍然有兴趣的解决方案，工作在Pig。