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https://issues.apache.org/jira/browse/HBASE-17887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16033257#comment-16033257
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Chia-Ping Tsai commented on HBASE-17887:
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HBASE-18145 is another bug about the row-level consistency.
> Row-level consistency is broken for read
> ----------------------------------------
>
> Key: HBASE-17887
> URL: https://issues.apache.org/jira/browse/HBASE-17887
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 2.0.0, 1.3.0
> Reporter: Umesh Agashe
> Assignee: Chia-Ping Tsai
> Priority: Blocker
> Fix For: 2.0.0, 1.4.0, 1.3.2
>
> Attachments: HBASE-17887.branch-1.v0.patch,
> HBASE-17887.branch-1.v1.patch, HBASE-17887.branch-1.v1.patch,
> HBASE-17887.branch-1.v2.patch, HBASE-17887.branch-1.v2.patch,
> HBASE-17887.branch-1.v3.patch, HBASE-17887.branch-1.v4.patch,
> HBASE-17887.branch-1.v4.patch, HBASE-17887.branch-1.v4.patch,
> HBASE-17887.branch-1.v5.patch, HBASE-17887.branch-1.v6.patch,
> HBASE-17887.ut.patch, HBASE-17887.v0.patch, HBASE-17887.v1.patch,
> HBASE-17887.v2.patch, HBASE-17887.v3.patch, HBASE-17887.v4.patch,
> HBASE-17887.v5.patch, HBASE-17887.v5.patch
>
>
> The scanner of latest memstore may be lost if we make quick flushes. The
> following step may help explain this issue.
> # put data_A (seq id = 10, active store data_A and snapshots is empty)
> # snapshot of 1st flush (active is empty and snapshot stores data_A)
> # put data_B (seq id = 11, active store data_B and snapshot store data_A)
> # create user scanner (read point = 11, so It should see the data_B)
> # commit of 1st flush
> #* clear snapshot ((hfile_A has data_A, active store data_B, and snapshot is
> empty)
> #* update the reader (the user scanner receives the hfile_A)
> # snapshot of 2st flush (active is empty and snapshot store data_B)
> # commit of 2st flush
> #* clear snapshot (hfile_A has data_A, hfile_B has data_B, active is empty,
> and snapshot is empty) – this is critical piece.
> #* -update the reader- (haven't happen)
> # user scanner update the kv scanners (it creates scanner of hfile_A but
> nothing of memstore)
> # user see the older data A – wrong result
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