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https://issues.apache.org/jira/browse/HBASE-15477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15206081#comment-15206081
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Anoop Sam John commented on HBASE-15477:
----------------------------------------
{code}
if (hFileBlock.hasNextBlockHeader()) {
181 hFileBlock.buf.limit(hFileBlock.buf.limit() -
hFileBlock.headerSize());
182 }
{code}
So this is removed now as we dont write next block's header with cur block..
So where is this change of avoiding it? When write in BC?
Also when this block is created out of a BB read from HDFS, that BB will
contain the next block's header also at the end. So we dont need this limiting
thing at all? How on those block's buffers we do the limit. (Some other place)
Because when reading cells, we will read until block's buf.hasRemaining()
> 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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