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https://issues.apache.org/jira/browse/HBASE-18066?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16015648#comment-16015648
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Zheng Hu edited comment on HBASE-18066 at 5/18/17 12:18 PM:
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[~timoha], Thanks for your report. Gist code your provided almost always
tested failed (for better testing, I upload a unit test), and after the check,
I think the problem is: the HRegion.getClosestRowBefore() method search the
closest existed rowKey without mvcc readpoint , but search the value by a scan
with the current mvcc readpoint & rowKey found in the previous step. So if
SplitRegion procedure put a Mutation into hbase:meta table, we may get the
closest rowKey but return a NONE KeyValue by a Get with closestRowBefore true ,
because we can not see the key-value in MVCC.
was (Author: openinx):
[~timoha], Thanks for your report. Gist code your provided almost always
tested failed (for better testing, I upload a unit test), and after the check,
I think the problem is: the HRegion.getClosestRowBefore() method search the
closest existed rowKey without mvcc readpoint , but search the value by a scan
with the current mvcc readpoint & rowKey found in the previous step. So if
SplitRegion procedure put a Mutation into hbase:meta table, we may get the
closest rowKey but return a NONE KeyValue by a Get with closestRowBefore true.
> Get with closest_row_before on "hbase:meta" can return empty Cell during
> region merge/split
> -------------------------------------------------------------------------------------------
>
> Key: HBASE-18066
> URL: https://issues.apache.org/jira/browse/HBASE-18066
> Project: HBase
> Issue Type: Bug
> Components: hbase, regionserver
> Affects Versions: 1.3.1
> Environment: Linux (16.04.2), MacOS 10.11.6.
> Standalone and distributed HBase setup.
> Reporter: Andrey Elenskiy
> Attachments: TestGetWithClosestRowBeforeWhenSplit.java
>
>
> During region split/merge there's a brief period of time where doing a "Get"
> with "closest_row_before=true" on "hbase:meta" may return empty
> "GetResponse.result.cell" field even though parent, splitA and splitB regions
> are all in "hbase:meta". Both gohbase (https://github.com/tsuna/gohbase) and
> AsyncHBase (https://github.com/OpenTSDB/asynchbase) interprets this as
> "TableDoesNotExist", which is returned to the client.
> Here's a gist that reproduces this problem:
> https://gist.github.com/Timoha/c7a236b768be9220e85e53e1ca53bf96. Note that
> you have to use older HTable client (I used 1.2.4) as current versions ignore
> `Get.setClosestRowBefore(bool)` option.
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