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https://issues.apache.org/jira/browse/HBASE-6874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13488448#comment-13488448
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Lars Hofhansl commented on HBASE-6874:
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[~karthik.ranga] Do you have a patch. We were just discussing something similar 
here and I was about to open a similar issue before I found this one. This is 
even more useful with scanner caching.

One could even go a step further and parallelize the prefetching into N threads 
(useful if the results are heavily prefiltered at the server).

We do our own parallel scanner fetching (not necessarily on region or buffer 
boundaries), but it would be nice if that could be generalized and be part of 
HBase.

                
> Implement prefetching for scanners
> ----------------------------------
>
>                 Key: HBASE-6874
>                 URL: https://issues.apache.org/jira/browse/HBASE-6874
>             Project: HBase
>          Issue Type: Sub-task
>            Reporter: Karthik Ranganathan
>            Assignee: Karthik Ranganathan
>
> I did some quick experiments by scanning data that should be completely in 
> memory and found that adding pre-fetching increases the throughput by about 
> 50% from 26MB/s to 39MB/s.
> The idea is to perform the next in a background thread, and keep the result 
> ready. When the scanner's next comes in, return the pre-computed result and 
> issue another background read.

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