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https://issues.apache.org/jira/browse/HBASE-3855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13408687#comment-13408687
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Jonathan Hsieh commented on HBASE-3855:
---------------------------------------
Ouch!
Yes, I think we'd like to get HBASE-4195 in o 0.90.7 as well -- not for
performance but for correctness reasons.
> Performance degradation of memstore because reseek is linear
> ------------------------------------------------------------
>
> Key: HBASE-3855
> URL: https://issues.apache.org/jira/browse/HBASE-3855
> Project: HBase
> Issue Type: Improvement
> Reporter: dhruba borthakur
> Priority: Critical
> Fix For: 0.90.4
>
> Attachments: memstoreReseek.txt, memstoreReseek2.txt
>
>
> The scanner use reseek to find the next row (or next column) as part of a
> scan. The reseek code iterates over a Set to position itself at the right
> place. If there are many thousands of kvs that need to be skipped over, then
> the time-cost is very high. In this case, a seek would be far lesser in cost
> than a reseek.
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