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https://issues.apache.org/jira/browse/HBASE-15477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15203767#comment-15203767
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Anoop Sam John commented on HBASE-15477:
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So in RB some where I see you said abt the usefulness of having the next
block's header in cur block. (When cur block comes from cache and next block
is to come from HDFS). So we will NOT do "Do not save 'next block header' when
we cache hfileblocks"?
> Do not save 'next block header' when we cache hfileblocks
> ---------------------------------------------------------
>
> Key: HBASE-15477
> URL: https://issues.apache.org/jira/browse/HBASE-15477
> Project: HBase
> Issue Type: Sub-task
> Components: BlockCache, Performance
> Reporter: stack
> Assignee: stack
> Attachments: 15366v4.patch, 15477.patch, 15477v2.patch,
> 15477v3.patch, 15477v3.patch, 15477v4.patch
>
>
> When we read from HDFS, we overread to pick up the next blocks header.
> Doing this saves a seek as we move through the hfile; we save having to
> do an explicit seek just to read the block header every time we need to
> read the body. We used to read in the next header as part of the
> current blocks buffer. This buffer was then what got persisted to
> blockcache; so we were over-persisting wrtiting out our block plus the
> next blocks' header (overpersisting 33 bytes). Parse of HFileBlock
> complicated by this extra tail. Fix.
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