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From Michael Segel <michael_se...@hotmail.com>
Subject Re: Coprocessor end point vs MapReduce?
Date Thu, 18 Oct 2012 00:27:30 GMT

I'm a firm believer in KISS (Keep It Simple, Stupid) 

The Map/Reduce (map job only) is the simplest and least prone to failure. 

Not sure why you would want to do this using coprocessors. 

How often are you running this job? It sounds like its going to be sporadic.


On Oct 17, 2012, at 7:11 PM, Jean-Marc Spaggiari <jean-marc@spaggiari.org> wrote:

> Hi,
> Can someone please help me to understand the pros and cons between
> those 2 options for the following usecase?
> I need to transfer all the rows between 2 timestamps to another table.
> My first idea was to run a MapReduce to map the rows and store them on
> another table, and then delete them using an end point coprocessor.
> But the more I look into it, the more I think the MapReduce is not a
> good idea and I should use a coprocessor instead.
> BUT... The MapReduce framework guarantee me that it will run against
> all the regions. I tried to stop a regionserver while the job was
> running. The region moved, and the MapReduce restarted the job from
> the new location. Will the coprocessor do the same thing?
> Also, I found the webconsole for the MapReduce with the number of
> jobs, the status, etc. Is there the same thing with the coprocessors?
> Are all coprocessors running at the same time on all regions, which
> mean we can have 100 of them running on a regionserver at a time? Or
> are they running like the MapReduce jobs based on some configured
> values?
> Thanks,
> JM

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