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Date: Tue, 4 Feb 2014 06:14:10 +0000 (UTC)
From: "ramkrishna.s.vasudevan (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
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Subject: [jira] [Commented] (HBASE-10447) Memstore flusher scans storefiles
 also when the scanner heap gets reset
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    [ https://issues.apache.org/jira/browse/HBASE-10447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13890431#comment-13890431 ] 

ramkrishna.s.vasudevan commented on HBASE-10447:
------------------------------------------------

Thanks Lars.
I was about to commit and once verified in 0.96 code.  There we don't add the observers even while doing compaction.
So should we make it like that in 0.98 and trunk also.  In the sense only for user reads the observers are added. The current change would any way add observers for compaction also as it was in 0.98 and trunk.  Would get this clarified once before I could commit it. Suggestions?

> Memstore flusher scans storefiles also when the scanner heap gets reset
> -----------------------------------------------------------------------
>
>                 Key: HBASE-10447
>                 URL: https://issues.apache.org/jira/browse/HBASE-10447
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.98.0, 0.99.0, 0.96.1.1
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>            Priority: Blocker
>             Fix For: 0.98.0, 0.96.2, 0.99.0
>
>         Attachments: HBASE-10447_0.98.patch, HBASE-10447_trunk.patch
>
>
> See the mail thread
> http://osdir.com/ml/general/2014-01/msg61294.html
> In case of flush we create a memstore flusher which in turn creates a  StoreScanner backed by a Single ton MemstoreScanner.  
> But this scanner also registers for any updates in the reader in the HStore.  Is this needed?  
> If this happens then any update on the reader may nullify the current heap and the entire Scanner Stack is reset, but this time with the other scanners for all the files that satisfies the last top key.  So the flush that happens on the memstore holds the storefile scanners also in the heap that was recreated but originally the intention was to create a scanner on the memstore alone.


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