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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11425) Cell/DBB end-to-end on the read-path
Date Mon, 30 Jun 2014 12:03:25 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11425?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14047590#comment-14047590

ramkrishna.s.vasudevan commented on HBASE-11425:

bq.Currently we copy the block cache bytes onheap to guard against the blocks being evicted
out from under us. We'll do reference counting?
I think this is one major area where we may have to work. If a block is currently getting
scanned set a reference and do not evict them.  On what basis should we select the next block
that can be evicted ? Need to do some more analysis on this.

> Cell/DBB end-to-end on the read-path
> ------------------------------------
>                 Key: HBASE-11425
>                 URL: https://issues.apache.org/jira/browse/HBASE-11425
>             Project: HBase
>          Issue Type: Umbrella
>          Components: regionserver, Scanners
>    Affects Versions: 0.99.0
>            Reporter: Anoop Sam John
>            Assignee: Anoop Sam John
> Umbrella jira to make sure we can have blocks cached in offheap backed cache. In the
entire read path, we can refer to this offheap buffer and avoid onheap copying.
> The high level items I can identify as of now are
> 1. Avoid the array() call on BB in read path.. (This is there in many classes. We can
handle class by class)
> 2. Support Buffer based getter APIs in cell.  In read path we will create a new Cell
with backed by BB. Will need in CellComparator, Filter (like SCVF), CPs etc.
> 3. Avoid KeyValue.ensureKeyValue() calls in read path - This make byte copy.
> 4. Remove all CP hooks (which are already deprecated) which deal with KVs.  (In read
> Will add subtasks under this.

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