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https://issues.apache.org/jira/browse/MAHOUT-376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12966368#action_12966368
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Ted Dunning commented on MAHOUT-376:
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{quote}
> This also raises the question of whether your combiner can be applied
> multiple times. I suspect yes. You will know better than I.
Yes, that's the optional hierarchy increment that i was talking about, that we
can additionally implement if billion for m and unbound n is not good enough.
{quote}
I think I wrote poorly here.
You don't get a choice. The frame will run the combiner as many times as it
feels it wants to. It will run in the mapper or reducer or both or neither.
Your combiner has to be ready to run any number of times on the output of the
mapper or the output of other combiners or a combination of the same. This
isn't optional in Hadoop. It may not have happened in the test runs you have
done, but that doesn't imply anything about whether it will happen at another
time.
> Implement Map-reduce version of stochastic SVD
> ----------------------------------------------
>
> Key: MAHOUT-376
> URL: https://issues.apache.org/jira/browse/MAHOUT-376
> Project: Mahout
> Issue Type: Improvement
> Components: Math
> Reporter: Ted Dunning
> Assignee: Ted Dunning
> Fix For: 0.5
>
> Attachments: MAHOUT-376.patch, Modified stochastic svd algorithm for
> mapreduce.pdf, QR decomposition for Map.pdf, QR decomposition for Map.pdf, QR
> decomposition for Map.pdf, sd-bib.bib, sd.pdf, sd.pdf, sd.pdf, sd.pdf,
> sd.tex, sd.tex, sd.tex, sd.tex, SSVD working notes.pdf, SSVD working
> notes.pdf, SSVD working notes.pdf, ssvd-CDH3-or-0.21.patch.gz,
> ssvd-CDH3-or-0.21.patch.gz, ssvd-m1.patch.gz, ssvd-m2.patch.gz,
> ssvd-m3.patch.gz, Stochastic SVD using eigensolver trick.pdf
>
>
> See attached pdf for outline of proposed method.
> All comments are welcome.
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