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From Koert Kuipers <ko...@tresata.com>
Subject Re: UDAF and group by
Date Sun, 04 Sep 2011 15:08:38 GMT
Hey, my question wasn't very clear. I have a UDAF that I apply per group.
The UDAF does not support terminatePartial() and merge(). So to do this i
run:

set hive.map.aggr=false;
select myUdf(col1, col2) from table group by col3;

Now this seems to work. But are my assumptions correct that this will never
call terminatePartial() or merge()?
Thanks Koert

On Thu, Sep 1, 2011 at 11:59 PM, Huan Li <yrlihuan@gmail.com> wrote:

> Koert, Not sure what you mean by "results can be merged between groups".
> UDAF should be used to aggregated records by group. Why need to merge
> between groups?
>
> Can you give some examples of what kind of query you'd like to run?
>
>
> 2011/8/30 Koert Kuipers <koert@tresata.com>
>
>> If i run my own UDAF with group by, can i be sure that a single UDAF
>> instance initialized once will process all members in a group? Or should i
>> code so as to take into account the situation where even within a group
>> multiple UDAFs could run, and i would have to deal with terminatePartial()
>> and merge() even within a group?
>> My problem is that my results within a group are not easily merged, but
>> between groups they are.
>>
>
>

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