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https://issues.apache.org/jira/browse/ACCUMULO-4500?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15592188#comment-15592188
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Josh Elser commented on ACCUMULO-4500:
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bq. 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.
I really don't want to get into an argument over semantics.
bq. What we have here is more general than even that, because we're not
necessarily referring to a single variable
I don't know this means.
{code}
public NamedCounters getCounters(Range range, Function<Long, Long> combiner);
{code}
I still don't understand what the {{Function<Long,Long>}} is accomplishing.
Combination of numbers is (typically) addition. Why do we need a function here?
Also, this doesn't let me fetch just the visibility data. If there are multiple
types of counters stored in the rfiles, how do I refer to just one? How do I
know which exist for some table?
bq. Re passing in an instance of a Function, how can we run the function on
remote JVMs? We could take the class name from the instance and use that to
instantiate on remote JVMs
This is 110% what I wanted to avoid. What was suggested as a *simple* database
primitive is now being exploded into a "wholly generalized user-configured
framework". I have no interest in working on that. If either of you do, I'm
happy to help sketch out such a system, but I will lose all interest in
building this simple feature if it's being stipulated that I have to build
something so largely different to build the proposed *simple* feature.
> 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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