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https://issues.apache.org/jira/browse/HBASE-3855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13405472#comment-13405472
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Gregory Chanan commented on HBASE-3855:
---------------------------------------
Addendum: I closed because I thought it was confusing to have an issue be open
when it was committed in 0.90.4 and never backed out [and no one is talking
about backing it out]. Perhaps we should create a new bug that tracks
backporting HBASE-4195 to 0.90 and, as Andrew suggests, put [0.90 branch] there?
> 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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