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https://issues.apache.org/jira/browse/HBASE-6874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13491695#comment-13491695
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Karthik Ranganathan commented on HBASE-6874:
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Lars - the dependency on HBASE-6770 is more to make the code simpler.
Currently, the HRegionServer loops over numRows, and the RegionScanner loops
over the columns in the various CF's but for one row. HBASE-6770 will move the
looping on the numRows into the RegionScanner itself, because we need to track
both memory size and number of rows - in order to respect the more restrictive
of the two. Once that happens, we can implement prefetching in the
RegionScanner itself, instead of spreading the logic in HRegionServer also. So
more of a code-simplicity and not having to resolve conflicts thing.
> 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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