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https://issues.apache.org/jira/browse/KUDU-749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16182119#comment-16182119
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Todd Lipcon commented on KUDU-749:
----------------------------------

FWIW this is still a pretty bad issue for YCSB workload A (zipfian 50/50 
read/update). The Apply thread is spending 75% of its time in 
DeltaMemStore::CheckRowDeleted. 

> Improve performance for zipfian update
> --------------------------------------
>
>                 Key: KUDU-749
>                 URL: https://issues.apache.org/jira/browse/KUDU-749
>             Project: Kudu
>          Issue Type: Improvement
>          Components: perf, tablet
>    Affects Versions: Private Beta
>            Reporter: Todd Lipcon
>         Attachments: screenshot-1.png, screenshot-2.png
>
>
> A zipfian 50/50 update/read workload on YCSB gets slower and slower until 
> it's pretty intolerable (random reads taking 100+ms of CPU). It seems like 
> all the CPU is spent in DMSIterator::PrepareBatch. We're probably doing 
> something dumb here - let's look for some low hanging fruit to fix this.



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