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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-9751) Excessive readpoints checks in StoreFileScanner
Date Sat, 12 Oct 2013 22:47:42 GMT

    [ https://issues.apache.org/jira/browse/HBASE-9751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13793516#comment-13793516
] 

Lars Hofhansl commented on HBASE-9751:
--------------------------------------

No it does not contradict. In fact they are saying the same thing.
If the reader can prove that it does not need the memstoreTS it won't use. You are removing
part of the code that does the proving.


> Excessive  readpoints checks in StoreFileScanner
> ------------------------------------------------
>
>                 Key: HBASE-9751
>                 URL: https://issues.apache.org/jira/browse/HBASE-9751
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.98.0, 0.94.12, 0.96.0
>            Reporter: Vladimir Rodionov
>            Assignee: Lars Hofhansl
>             Fix For: 0.98.0, 0.94.13, 0.96.1
>
>         Attachments: 9751-0.94.txt, 9751-trunk.txt
>
>
> It seems that usage of skipKVsNewerThanReadpoint in StoreFileScanner can be greatly reduced
or even eliminated all together (HFiles are immutable and no new KVs can be inserted after
scanner instance is created). The same is true for MemStoreScanner which checks readpoint
on every next() and seek(). Each readpoint check is ThreadLocal.get() and it is quite expensive.
 



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