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https://issues.apache.org/jira/browse/HBASE-10227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13858222#comment-13858222
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Feng Honghua commented on HBASE-10227:
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[~gustavoanatoly] : sounds good. I will also try to find time to extract the
original fix for it from jira-8721 these days to attach here for your reference.
> When a region is opened, its mvcc isn't correctly recovered when there are
> split hlogs to replay
> ------------------------------------------------------------------------------------------------
>
> Key: HBASE-10227
> URL: https://issues.apache.org/jira/browse/HBASE-10227
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Reporter: Feng Honghua
> Assignee: Gustavo Anatoly
>
> When opening a region, all stores are examined to get the max MemstoreTS and
> it's used as the initial mvcc for the region, and then split hlogs are
> replayed. In fact the edits in split hlogs have kvs with greater mvcc than
> all MemstoreTS in all store files, but replaying them don't increment the
> mvcc according at all. From an overall perspective this mvcc recovering is
> 'logically' incorrect/incomplete.
> Why currently it doesn't incur problem is because no active scanners exists
> and no new scanners can be created before the region opening completes, so
> the mvcc of all kvs in the resulted hfiles from hlog replaying can be safely
> set to zero. They are just treated as kvs put 'earlier' than the ones in
> HFiles with mvcc greater than zero(say 'earlier' since they have mvcc less
> than the ones with non-zero mvcc, but in fact they are put 'later'), and
> without any incorrect impact just because during region opening there are no
> active scanners existing / created.
> This bug is just in 'logic' sense for the time being, but if later on we need
> to survive mvcc in the region's whole logic lifecycle(across regionservers)
> and never set them to zero, this bug needs to be fixed first.
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