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https://issues.apache.org/jira/browse/HBASE-19722?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16491048#comment-16491048
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Xu Cang commented on HBASE-19722:
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"at most 1/e meters will be kept" — There is a typo here. It should be ' 7 /
e' according to the paper:
([https://micvog.files.wordpress.com/2015/06/approximate_freq_count_over_data_streams_vldb_2002.pdf]
See paragraph above chapter 4.3)
This 7 / e space is still good to me. For example, if we use 0.02 as error
rate, at most 350 meters will be kept.
Lossy counting algorithm designed the sweeping happens every "1 / errorRate"
items arrived. For example, if e is 0.02, sweep() method will be called every
50 times.
Yes, I can try to make 'e' configurable from site config.
"Ideally the operator could be able to set the number of expected top-N, e.g. N
= 100" – that's a good idea. Let me see if there is a good conversion from e to
N in topN.
Yes, I will fix findbugs errors. And add ASF header.
Thanks for the review, Andrew.
> Implement a meta query statistics metrics source
> ------------------------------------------------
>
> Key: HBASE-19722
> URL: https://issues.apache.org/jira/browse/HBASE-19722
> Project: HBase
> Issue Type: Sub-task
> Reporter: Andrew Purtell
> Assignee: Xu Cang
> Priority: Major
> Attachments: HBASE-19722.branch-1.v001.patch,
> HBASE-19722.master.010.patch, HBASE-19722.master.011.patch,
> HBASE-19722.master.012.patch, HBASE-19722.master.013.patch
>
>
> Implement a meta query statistics metrics source, created whenever a
> regionserver starts hosting meta, removed when meta hosting moves. Provide
> views on top tables by request counts, top meta rowkeys by request count, top
> clients making requests by their hostname.
> Can be implemented as a coprocessor.
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