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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (HBASE-3718) Improve 'get' performance when row resides in memstore
Date Mon, 29 Dec 2014 19:53:13 GMT

     [ https://issues.apache.org/jira/browse/HBASE-3718?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

stack resolved HBASE-3718.
    Resolution: Won't Fix

Suggestion to give up range scan on some tables so can use ConcurrentHashMap instead of skiplist
 Resolving as won't fix.

> Improve 'get' performance when row resides in memstore
> ------------------------------------------------------
>                 Key: HBASE-3718
>                 URL: https://issues.apache.org/jira/browse/HBASE-3718
>             Project: HBase
>          Issue Type: Improvement
>          Components: regionserver
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
> The regionserver uses a ConcurrentSkipList to store the KVs in the memstore. Although
the order complexity of a lookup is O(n), still the latency to lookup a specific key in the
memstore is very large, especially when the memstore is large and the KV.compare() method
is costly.
> One optimization is to investigate using a ConcurrentHashMap (instead of ConcurrentSkipList).
The lookup and insertion cost is minimized. We can do it only for column-families that are
marked as "do not support rangescans". 

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