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https://issues.apache.org/jira/browse/HBASE-9751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13793256#comment-13793256
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Vladimir Rodionov commented on HBASE-9751:
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The possible optimization won't give much performance improvement unless tested
directly on MemStoreScanner. There are many others performance issues on a
scanner read path which will obscure the performance gain. The major offenders:
* new instance of KeyValue on every StoreScanner.next() (regardless of Filter
selectivity).
* sub-par implementation of :
ScanQueryMatcher.MatchCode qcode = matcher.match(kv); in
StoreScanner.next()
ScanQueryMatcher code is responsible for > 50% of execution time of of
StoreScanner.next().
Object creation in Java becomes expensive in MT mode.
> Excessive readpoints checks in MemStoreScanner and 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
>
> 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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