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https://issues.apache.org/jira/browse/HBASE-17849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15948063#comment-15948063
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Enis Soztutar commented on HBASE-17849:
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I have noticed something like this as well where the regions generated from
pre-split are not growing at the equal rate. Especially the last region(s) are
relatively small.
> PE tool randomness is not totally random
> ----------------------------------------
>
> Key: HBASE-17849
> URL: https://issues.apache.org/jira/browse/HBASE-17849
> Project: HBase
> Issue Type: Bug
> Components: test
> Affects Versions: 2.0.0
> Reporter: ramkrishna.s.vasudevan
> Fix For: 2.0.0
>
>
> Recently we were using the PE tool for doing some bucket cache related
> performance tests. One thing that we noted was that the way the random read
> works is not totally random.
> Suppose we load 200G of data using --size param and then we use --rows=500000
> to do the randomRead. The assumption was among the 200G of data it could
> generate randomly 500000 row keys to do the reads.
> But it so happens that the PE tool generates random rows only on those set of
> row keys which falls under the first 500000 rows.
> This was quite evident when we tried to use HBASE-15314 in our testing.
> Suppose we split the bucket cache of size 200G into 2 files each 100G the
> randomReads with --rows=500000 always lands in the first file and not in the
> 2nd file. Better to make PE purely random.
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