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https://issues.apache.org/jira/browse/PHOENIX-418?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16141100#comment-16141100
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Josh Elser commented on PHOENIX-418:
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[~jamestaylor], thanks for thinking about the licensing! Turns out, there is
something that we should propagate in the binary tarball
https://github.com/addthis/stream-lib/blob/master/NOTICE.txt
Specifically, we should include text, something like:
{noformat}
stream-lib
Copyright 2016 AddThis
This product includes software developed by AddThis.
{noformat}
Aside, it appears that there is a 2.9.5 version of
{{com.clearspring.analytics:stream}} in maven-central. Is there a reason for us
to use 2.7.0, specifically?
Neat little change, Ethan. I look forward to playing around with the feature :)
> Support approximate COUNT DISTINCT
> ----------------------------------
>
> Key: PHOENIX-418
> URL: https://issues.apache.org/jira/browse/PHOENIX-418
> Project: Phoenix
> Issue Type: Task
> Reporter: James Taylor
> Assignee: Ethan Wang
> Labels: gsoc2016
> Attachments: PHOENIX-418-v1.patch, PHOENIX-418-v2.patch,
> PHOENIX-418-v3.patch, PHOENIX-418-v4.patch, PHOENIX-418-v5.patch,
> PHOENIX-418-v6.patch
>
>
> Support an "approximation" of count distinct to prevent having to hold on to
> all distinct values (since this will not scale well when the number of
> distinct values is huge). The Apache Drill folks have had some interesting
> discussions on this
> [here](http://mail-archives.apache.org/mod_mbox/incubator-drill-dev/201306.mbox/%3CJIRA.12650169.1369931282407.88049.1370645900553%40arcas%3E).
> They recommend using [Welford's
> method](http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance_Online_algorithm).
> I'm open to having a config option that uses exact versus approximate. I
> don't have experience implementing an approximate implementation, so I'm not
> sure how much state is required to keep on the server and return to the
> client (other than realizing it'd be much less that returning all distinct
> values and their counts).
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