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From "Anastasia Braginsky (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16438) Create a cell type so that chunk id is embedded in it
Date Sun, 02 Apr 2017 12:45:42 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15952657#comment-15952657
] 

Anastasia Braginsky commented on HBASE-16438:
---------------------------------------------

As I am reviving the CellChunkMap now, having cell-representation of size of 24 bytes, sounds
way too much for me.

Per Cell we save: chunk ID (long - 8 bytes), offset (int - 4 bytes), length (int - 4 bytes),
seqID (long - 8 bytes).

Can someone explain me why is it a must to keep the seqID there?

For chunk ID, can 4 bytes int be enough? If we are running out of 2^31 positive numbers we
may start using the next 2^31 negative numbers... 
Having 2^32 chunks sounds quite enough. With the current chunk size (2MB=2^21 bytes) we can
cover 8 PetaBytes per RS, or we can increase size of chunk...
Thoughts?

> 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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