[jira] [Commented] (HBASE-9102) HFile block pre-loading for large sequential scan

["Lars Hofhansl (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-9102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13725446#comment-13725446 ] 

Lars Hofhansl commented on HBASE-9102:
--------------------------------------

Should we handle this from the client instead. Part of the problem is that the network pipe is not kept full, so by triggering prefetching from the client we can solve both problems.
                
> 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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