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From Ido Hadanny <ido.hada...@gmail.com>
Subject Re: why is data.fu implementing HyperLogLog as an accumulator and not as algebraic?
Date Tue, 28 Apr 2015 05:37:03 GMT
https://issues.apache.org/jira/browse/DATAFU-91


On 27 April 2015 at 18:02, Matthew Hayes <matthew.terence.hayes@gmail.com>
wrote:

> Great thanks :) Please file a JIRA and attach the patch there.
>
> -Matt
>
> On Apr 27, 2015, at 6:26 AM, Ido Hadanny <ido.hadanny@gmail.com> wrote:
>
> Hey guys,
> patch is attached + tested on unit-tests + We're testing it on a
> 1000-nodes real hadoop cluster as we speak.
> Do you want us to create a jira issue for this, or is this good enough?
> Thanks, Ilia and Ido
>
> On 7 March 2015 at 23:09, Matthew Hayes <matthew.terence.hayes@gmail.com>
> wrote:
>
>> I don't remember if there was a particular reason I didn't implement this
>> as AlgebraicEvalFunc. It seems like it could be. I believe the Java
>> MapReduce version leverages the combiner. If you want to try making this
>> Algebraic we would be happy to accept a patch :)
>>
>> -Matt
>>
>> > On Mar 7, 2015, at 12:11 PM, Ido Hadanny <ido.hadanny@gmail.com> wrote:
>> >
>> > data.fu has a nice implementation of HyperLogLog for estimating
>> cardinality
>> > here
>> > <
>> https://github.com/apache/incubator-datafu/blob/master/datafu-pig/src/main/java/datafu/pig/stats/HyperLogLogPlusPlus.java
>> >
>> >
>> > However, it's implemented as Accumulator which means it will run only at
>> > the reducer and not in the combiner (but it will never load the entire
>> set
>> > into memory as in normal EvalFunc). Why couldn't data.fu implement it as
>> > Algebraic - and fill the registers at every combiner, then merge and
>> reduce
>> > the result? Am I missing something here?
>> > also available here:
>> >
>> http://stackoverflow.com/questions/28908217/why-is-data-fu-implementing-hyperloglog-as-an-accumulator-and-not-as-algebraic
>> >
>> > thanks!
>> >
>> >
>> > --
>> > Sent from my androido
>>
>
>
>
> --
> Sent from my androido
>
> <hyper-log-log-algebraic.diff>
>
>


-- 
Sent from my androido

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