Hive: writing column headers to local file?

Question

Hive documentation lacking again:

I\'d like to write the results of a query to a local file as well as the names of the columns.

Does Hive support this?

Answer 1

I ran into this problem today and was able to get what I needed by doing a UNION ALL between the original query and a new dummy query that creates the header row. I added a sort column on each section and set the header to 0 and the data to a 1 so I could sort by that field and ensure the header row came out on top.

create table new_table as
select 
  field1,
  field2,
  field3
from
(
  select
    0 as sort_col,  --header row gets lowest number
    'field1_name' as field1,
    'field2_name' as field2,
    'field3_name' as field3
  from
    some_small_table  --table needs at least 1 row
  limit 1  --only need 1 header row
  union all
  select
    1 as sort_col,  --original query goes here
    field1,
    field2,
    field3
  from
    main_table
) a
order by 
  sort_col  --make sure header row is first

It's a little bulky, but at least you can get what you need with a single query.

Hope this helps!