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From abhinit <abhinit.ku...@gmail.com>
Subject Re: implementing selection/projection using mapreduce
Date Fri, 05 Dec 2008 05:05:38 GMT
Thanks. ONe more thing.

How do you get the current configuration object in the map method.
I couldn't find it.

Thanks,
-Abhinit


Try passing the variables into the mapper through the JobConf.set
and .get methods.

On Dec 4, 2008, at 3:45 AM, abhinit wrote:

> Hi,
>
> I am implementing basic selection/projection using mapreduce on an
> HBase
> table.
>
> I have an outer class SelectProject which implements the tool
> interface and
> my mapper class,
> SelectProjectOperator extends TableMap.
>
> In my run method, I am parsing the command line argument for things
> like
> column names
> and predicate condition(say key = 10000 etc.) and I have to use
> these values
> inside the map
> method of my mapper class. All the variables to be used in the map
> function
> for selection/projection
> are static variables of the enclosing outer class(SelectProject). I
> et these
> variables in run method
> after parsing the comman-line arguments.
>
> However, in the map method I get a NullPointerException because non-
> of those
> static member variables
> are created. I understand this is not exactlt an HBase related issue
> and has
> something to do with java inner classes.
> But I thought this can be a very common case in mapreduce programming
> (passing a condition variable from the
> outer class to enclosed mapper class' map method).
>
> Thanks a lot for help.
> -Abhinit
>
> --

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