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HBase, mail # user - Coprocessor end point vs MapReduce?


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Re: Coprocessor end point vs MapReduce?
Michael Segel 2012-10-18, 18:01
Doug,

One thing that concerns me is that a lot of folks are gravitating to Coprocessors and may be using them for the wrong thing.
Has anyone done any sort of research as to some of the limitations and negative impacts on using coprocessors?

While I haven't really toyed with the idea of bulk deletes, periodic deletes is probably not a good use of coprocessors.... however using them to synchronize tables would be a valid use case.

Thx

-Mike

On Oct 18, 2012, at 7:36 AM, Doug Meil <[EMAIL PROTECTED]> wrote:

>
> To echo what Mike said about KISS, would you use triggers for a large
> time-sensitive batch job in an RDBMS?  It's possible, but probably not.
> Then you might want to think twice about using co-processors for such a
> purpose with HBase.
>
>
>
>
>
> On 10/17/12 9:50 PM, "Michael Segel" <[EMAIL PROTECTED]> wrote:
>
>> Run your weekly job in a low priority fair scheduler/capacity scheduler
>> queue.
>>
>> Maybe its just me, but I look at Coprocessors as a similar structure to
>> RDBMS triggers and stored procedures.
>> You need to restrain and use them sparingly otherwise you end up creating
>> performance issues.
>>
>> Just IMHO.
>>
>> -Mike
>>
>> On Oct 17, 2012, at 8:44 PM, Jean-Marc Spaggiari
>> <[EMAIL PROTECTED]> wrote:
>>
>>> I don't have any concern about the time it's taking. It's more about
>>> the load it's putting on the cluster. I have other jobs that I need to
>>> run (secondary index, data processing, etc.). So the more time this
>>> new job is taking, the less CPU the others will have.
>>>
>>> I tried the M/R and I really liked the way it's done. So my only
>>> concern will really be the performance of the delete part.
>>>
>>> That's why I'm wondering what's the best practice to move a row to
>>> another table.
>>>
>>> 2012/10/17, Michael Segel <[EMAIL PROTECTED]>:
>>>> If you're going to be running this weekly, I would suggest that you
>>>> stick
>>>> with the M/R job.
>>>>
>>>> Is there any reason why you need to be worried about the time it takes
>>>> to do
>>>> the deletes?
>>>>
>>>>
>>>> On Oct 17, 2012, at 8:19 PM, Jean-Marc Spaggiari
>>>> <[EMAIL PROTECTED]>
>>>> wrote:
>>>>
>>>>> Hi Mike,
>>>>>
>>>>> I'm expecting to run the job weekly. I initially thought about using
>>>>> end points because I found HBASE-6942 which was a good example for my
>>>>> needs.
>>>>>
>>>>> I'm fine with the Put part for the Map/Reduce, but I'm not sure about
>>>>> the delete. That's why I look at coprocessors. Then I figure that I
>>>>> also can do the Put on the coprocessor side.
>>>>>
>>>>> On a M/R, can I delete the row I'm dealing with based on some criteria
>>>>> like timestamp? If I do that, I will not do bulk deletes, but I will
>>>>> delete the rows one by one, right? Which might be very slow.
>>>>>
>>>>> If in the future I want to run the job daily, might that be an issue?
>>>>>
>>>>> Or should I go with the initial idea of doing the Put with the M/R job
>>>>> and the delete with HBASE-6942?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> JM
>>>>>
>>>>>
>>>>> 2012/10/17, Michael Segel <[EMAIL PROTECTED]>:
>>>>>> Hi,
>>>>>>
>>>>>> 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.
>>>>>>
>>>>>> -Mike
>>>>>>
>>>>>> On Oct 17, 2012, at 7:11 PM, Jean-Marc Spaggiari
>>>>>> <[EMAIL PROTECTED]>
>>>>>> 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.