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https://issues.apache.org/jira/browse/HBASE-9102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13725453#comment-13725453
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Vladimir Rodionov commented on HBASE-9102:
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This is what, actually, OS does and all modern disk controllers do on a lower 
lvel. If short-circuit reads are enabled and HBase cluster has good HDFS 
locality and data is compacted you will get dick blocks pre-fetching for free. 
                
> HFile block pre-loading for large sequential scan
> -------------------------------------------------
>
>                 Key: HBASE-9102
>                 URL: https://issues.apache.org/jira/browse/HBASE-9102
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.89-fb
>            Reporter: Liyin Tang
>            Assignee: Liyin Tang
>
> The current HBase scan model cannot take full advantage of the aggrediate 
> disk throughput, especially for the large sequential scan cases. And for the 
> large sequential scan, it is easy to predict what the next block to read in 
> advance so that it can pre-load and decompress/decoded these data blocks from 
> HDFS into block cache right before the current read point. 
> Therefore, this jira is to optimized the large sequential scan performance by 
> pre-loading the HFile blocks into the block cache in a stream fashion so that 
> the scan query can read from the cache directly.

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