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https://issues.apache.org/jira/browse/HBASE-17407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15795278#comment-15795278
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Eshcar Hillel commented on HBASE-17407:
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Updating the WAL is not done in one atomic step;
It starts with startCacheFlush(), ends with completeCacheFlush() and it can
recover from crashes (via abortCacheFlush()) that happen between its starting
and ending point.
finalizeFlush() is invoked between start and complete. In this a period the
WAL state can be inconsistent.
Removing finalizeFlush means that we need to change the current (common) path
for updating the wal. This is something we tried to avoid in the original
design.
With HBASE-17081 flushing the tail becomes optional and not the default.
If this path will not be used in most cases it is better to leave the current
path for updating the WAL as is.
But still there's the issue of correctly updating maxFlushedSeqId after the
flush is completed.
> Correct update of maxFlushedSeqId in HRegion
> --------------------------------------------
>
> Key: HBASE-17407
> URL: https://issues.apache.org/jira/browse/HBASE-17407
> Project: HBase
> Issue Type: Bug
> Reporter: Eshcar Hillel
>
> The attribute maxFlushedSeqId in HRegion is used to track the max sequence id
> in the store files and is reported to HMaster. When flushing only part of the
> memstore content this value might be incorrect and may cause data loss.
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