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https://issues.apache.org/jira/browse/ACCUMULO-4500?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15589044#comment-15589044
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Christopher Tubbs commented on ACCUMULO-4500:
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bq. :coughs: That... is a histogram.
I disagree. A histogram is a diagram... a particular kind of data
visualization. Computer scientists overload the term to mean to mean the data
structure to power such a visualization, and that's fine, but that's not even
what we have here. A histogram has particular semantics where different values
of a single variable are on one axis, and the frequency of those values are
shown on the other. What we have here is more general than even that, because
we're not necessarily referring to a single variable, nor do the magnitudes
necessarily represent frequencies or anything like frequencies. Calling it a
histogram implies semantics we don't necessarily need to impose.
bq. Can you sketch what you think this should look like? It's not entirely
clear to me.
Something like:
{code:java}
public NamedCounters getCounters(Range range, Function<Long, Long> combiner);
{code}
bq. Keith had made a good point elsewhere that, when files overlap tablets, we
might double-count. That, combined with the counting (presently) not included
on the IMM, these "counters" (winks) would not be 100% accurate. Personally, I
think that's OK.
I agree.
bq. Example of another aggregation function?
Here's some: https://en.wikipedia.org/wiki/Aggregate_function
I could think of others.
> Implement visibility histograms as a table feature
> --------------------------------------------------
>
> Key: ACCUMULO-4500
> URL: https://issues.apache.org/jira/browse/ACCUMULO-4500
> Project: Accumulo
> Issue Type: New Feature
> Components: client, tserver
> Reporter: Josh Elser
>
> Add support to quickly extract a histogram of all of the visibilities stored
> in an Accumulo table.
> DISCUSS:
> https://lists.apache.org/thread.html/df5e764362a95277344fd2731a432e9fafc60595e7d30015d9a56b9c@%3Cdev.accumulo.apache.org%3E
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