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https://issues.apache.org/jira/browse/HBASE-9102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13726635#comment-13726635
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Liyin Tang commented on HBASE-9102:
-----------------------------------
Chao, You are right that the pre-load will run in a rate/limit fashion to make
sure it won't pollute the block cache substantially.
The pre-loading targets on the large sequential scan case. The client is able
to enable/disable on each request basis.
> 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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