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From Hanifi Gunes <hgu...@maprtech.com>
Subject Re: Apache Drill: How does the plug-in know that an aggregate function is applied
Date Mon, 10 Aug 2015 17:57:05 GMT
+dev

+1 to Hakim. AbstractRR#isSkipQuery is the way to go. If you want more
details on this you should check out DRILL-2358[1] that is an umbrella
issue targeting to make count(*) queries more efficient per storage plugin.
Currently (I guess) JSON and Mongo(?) readers support it though.

1:
https://github.com/apache/drill/commit/54df129cab544c3df8e75a7dae3f85a91a9ded5a

On Thu, Aug 6, 2015 at 6:50 PM, Abdel Hakim Deneche <adeneche@maprtech.com>
wrote:

> Hi Sudip,
>
> I'm not really an expert in this matter but I came recently across
> isSkipQuery() method in AbstractRecordReader, it's javadoc states:
>
> *Returns true if reader should skip all of the columns, reporting number of
> > records only. Handling of a skip query is storage plugin-specific.*
>
>
> You can take a look at JSONRecordReader for an example on how to use
> isSkipQuery() to optimize the reading.
>
> Thanks
>
> On Thu, Aug 6, 2015 at 2:01 AM, Sudip Mukherjee <
> mukherjeesudip1@hotmail.com
> > wrote:
>
> > Hi,
> > I am using apache drill recently with mongodb and trying to write a basic
> > plug-in for apache solr. Wanted to know how does the plug-in know that an
> > count(*) query has been applied so that the query to data-source can be
> > optimized? Can i get it if I extend  AbstractExprVisitor class?
> >
> > Thanks,Sudip Mukherjee
>
>
>
>
> --
>
> Abdelhakim Deneche
>
> Software Engineer
>
>   <http://www.mapr.com/>
>
>
> Now Available - Free Hadoop On-Demand Training
> <
> http://www.mapr.com/training?utm_source=Email&utm_medium=Signature&utm_campaign=Free%20available
> >
>

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