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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15554) StoreFile$Writer.appendGeneralBloomFilter generates extra KV
Date Tue, 10 May 2016 14:36:12 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15554?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15278186#comment-15278186
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ramkrishna.s.vasudevan commented on HBASE-15554:
------------------------------------------------

bq.It can avoid copy when the entire Key is in one buffer only right? The KeyValue way?
Exactly. So mark those Cells which wil have the buffer under only structure either in byte[]
or BB. So we will have KeyValue, OffheapKeyvalue, OnheapDecodedCell and OffheapDecodedcell.
All these are our internal cell representations. We can mark these cells for a special interface
type and add getKeyArray and getKeyBuffer() APIs in them. KeyValue already has getBuffer()
which we thought of deprecating but in write flow such as this we will need them.
In the bloom filter addition try to see if the cell is of the new interface type if so just
retrieve the key part from the cell directly and ensure that the Hash alogs/Bloom filter interfaces
have APIs to deal with ByteBuffers. With that we can avoid this copy.
But the catch is that we cannot write the blooms without the CF name. We have to write it
with the CF name. And hence I was suggesting that a major compaction would be needed. If we
see this information as redundant then we cannot do anything without copying the Key part
to a byte[] and doing as attached in the first patch here.

> StoreFile$Writer.appendGeneralBloomFilter generates extra KV
> ------------------------------------------------------------
>
>                 Key: HBASE-15554
>                 URL: https://issues.apache.org/jira/browse/HBASE-15554
>             Project: HBase
>          Issue Type: Sub-task
>          Components: Performance
>            Reporter: Vladimir Rodionov
>            Assignee: ramkrishna.s.vasudevan
>             Fix For: 2.0.0
>
>         Attachments: HBASE-15554.patch
>
>
> Accounts for 10% memory allocation in compaction thread when BloomFilterType is ROWCOL.



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