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https://issues.apache.org/jira/browse/HBASE-14949?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15074690#comment-15074690
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Duo Zhang commented on HBASE-14949:
-----------------------------------

{quote}
If we move sync WAL before update memstore, HBASE-14004 will be fixed naturally 
right? 
{quote}
No.
If we do not change the logic of WAL, sync failed does not mean the WAL entry 
is NOT write into the WAL file. This is the root cause of inconsistency.

> Skip duplicate entries when replay WAL.
> ---------------------------------------
>
>                 Key: HBASE-14949
>                 URL: https://issues.apache.org/jira/browse/HBASE-14949
>             Project: HBase
>          Issue Type: Sub-task
>            Reporter: Heng Chen
>         Attachments: HBASE-14949.patch, HBASE-14949_v1.patch, 
> HBASE-14949_v2.patch
>
>
> As HBASE-14004 design,  there will be duplicate entries in different WAL.  It 
> happens when one hflush failed, we will close old WAL with 'acked hflushed' 
> length,  then open a new WAL and write the unacked hlushed entries into it.
> So there maybe some overlap between old WAL and new WAL.
> We should skip the duplicate entries when replay.  I think it has no harm to 
> current logic, maybe we do it first. 



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