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From "Anoop Sam John (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16438) Create a cell type so that chunk id is embedded in it
Date Mon, 03 Apr 2017 09:52:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15953207#comment-15953207
] 

Anoop Sam John commented on HBASE-16438:
----------------------------------------

bq.Do you mean the seqID is going to be written in index-chunk only and is not going to be
written in the main-chunk, holding key, value and etc.? So no duplication? Are you sure? If
so, then already little better, but still I would like to keep the Cell meta data smaller.
Yes. Either to main chunk or to meta data chunk. As of now, it has to be in the meta chunk..
Ya we can change that if we make a new Cell impl for representing the cells added to the MSLAB.
( Seems we have one already). One more issue is u will need some more refactoring at the base
classes level so that u have a class to extend here. BBKV u can not as that is already having
a long state for seqId (wasting 8 bytes on heap space per cell).
bq.Why can not the existing BBKV just have a new method - getChunkId() - to return the chunk
id in the 0th offset of the backing BB
The cell impl BBKV might be used elsewhere also where its data is NOT in MSLAB chunks.  So
blindly reading 1st 4 bytes of the chunk's backing buffer is not correct. You need a new Cell
impl with this way of impl for the getChunkId() method.   I see this method is added to ExtendedCell
now.  So other impls of the ExtendedCell (Like KV) will throw Exception?

> Create a cell type so that chunk id is embedded in it
> -----------------------------------------------------
>
>                 Key: HBASE-16438
>                 URL: https://issues.apache.org/jira/browse/HBASE-16438
>             Project: HBase
>          Issue Type: Sub-task
>    Affects Versions: 2.0.0
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>         Attachments: HBASE-16438_1.patch, HBASE-16438_3_ChunkCreatorwrappingChunkPool.patch,
HBASE-16438_4_ChunkCreatorwrappingChunkPool.patch, HBASE-16438_8_ChunkCreatorwrappingChunkPool_withchunkRef.patch,
HBASE-16438_9_ChunkCreatorwrappingChunkPool_withchunkRef.patch, HBASE-16438.patch, MemstoreChunkCell_memstoreChunkCreator_oldversion.patch,
MemstoreChunkCell_trunk.patch
>
>
> For CellChunkMap we may need a cell such that the chunk out of which it was created,
the id of the chunk be embedded in it so that when doing flattening we can use the chunk id
as a meta data. More details will follow once the initial tasks are completed. 
> Why we need to embed the chunkid in the Cell is described by [~anastas] in this remark
over in parent issue https://issues.apache.org/jira/browse/HBASE-14921?focusedCommentId=15244119&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15244119



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