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https://issues.apache.org/jira/browse/HBASE-12295?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14590051#comment-14590051
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stack commented on HBASE-12295:
-------------------------------
Chatted w/ [~ram_krish] and [~anoopsamjohn] about cell-based vs scan-based
approach doing refcounting. They argued cell-based would involve a finer level
of accounting and that it will have to be done in many locations -- e.g. check
return from filters -- makes this approach untenable. Another strong objection
was that the assumption that we backing BB location zero was start of a block
is actually wrong (a block will be made of many fixed sized BBs from
bucketcache... location zero could be start of any one of these bucketcache
BBs). So, RPC call-backs across the great 'call' divide at the end of a session
with the callback going all the ways down the scan stack and into the
HFileBlock for it to do ref counting is the way to go.
> Prevent block eviction under us if reads are in progress from the BBs
> ---------------------------------------------------------------------
>
> Key: HBASE-12295
> URL: https://issues.apache.org/jira/browse/HBASE-12295
> Project: HBase
> Issue Type: Sub-task
> Components: regionserver, Scanners
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Fix For: 2.0.0
>
> Attachments: HBASE-12295.pdf, HBASE-12295_1.patch, HBASE-12295_1.pdf,
> HBASE-12295_2.patch, HBASE-12295_4.patch, HBASE-12295_4.pdf,
> HBASE-12295_5.pdf, HBASE-12295_trunk.patch
>
>
> While we try to serve the reads from the BBs directly from the block cache,
> we need to ensure that the blocks does not get evicted under us while
> reading. This JIRA is to discuss and implement a strategy for the same.
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