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From Ted Dunning <ted.dunn...@gmail.com>
Subject Re: Basic queries regarding Apache Drill working
Date Thu, 04 Apr 2013 13:27:20 GMT
On Thu, Apr 4, 2013 at 12:27 PM, devansh kumar <devansh_kumar@yahoo.com>wrote:

> Hi,
>
> I am new and am trying to understand how Apache Drill  works but i have a
> few queries.
> Can anyone help me understand these things?
>
> 1.
> I am trying to understand if the execution engine is going to break up the
> data.
>

Normally the data will already have been broken up across a cluster.


> What will happen if i am trying to an aggregation operation like (AVERAGE).
> How will that work??
>

Yes.


> I have seen operations as SUM and COUNT.
> How will the Query execution tree look like in case of an AVERAGE
>

It will look exactly like a SUM or COUNT except that two numbers will be
accumulated instead of one.


> 2.
> Does the Resource model is optimized when compared to MapReduce.
>

Yes.  This will happen because multiple levels of aggregation can be done
in one tree without the barrier between map and reduce imposed by the
MapReduce structure.

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