Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Plain View
Hive >> mail # user >> unexplode?


+
Mike Fleming 2012-08-23, 16:45
+
Philip Tromans 2012-08-23, 17:26
Also I have a colllect udf.
https://github.com/edwardcapriolo/hive-collect

Since collect sets removes duplicates.

On Thu, Aug 23, 2012 at 1:26 PM, Philip Tromans
<[EMAIL PROTECTED]> wrote:
> insert into originalTable
> select uniqueId, collect_set(whatever) from explodedTable group by uniqueId
>
> will probably do the trick.
>
> Phil.
>
> On 23 August 2012 17:45, Mike Fleming <[EMAIL PROTECTED]> wrote:
>> I see that hive has away to take a table and produce multiple rows.
>>
>> Is there a built in way to do the reverse?
>>
>> Say I have a table with a unique key and an array. I do this:
>>
>>> insert into explodedTable select uniqueId, explode(arrayOfThings) from
>>> originalTable
>>
>> Now I have a table with a row for each (uniqueId, element in arrayOfThings).
>>
>> Is there any way to take the contents of explodedTable and essentially
>> produce the original table, reconstructing the arrayOfThings for each
>> uniqueId?
>>
>> It seems, conceptually, that if I "cluster by uniqueId" then a reducer knows
>> that it will get all rows for each uniqueId bundled together, so it ought to
>> be fairly feasible to simply emit an unexploded row. However, I can't seem
>> to find a built-in way to do this.
>>
>> Mike
>>