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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 Mon, 13 Mar 2017 13:16:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15907440#comment-15907440

Anastasia Braginsky commented on HBASE-16438:

Hey [~ram_krish]!
Thanks for publishing the new patch! I have looked on it, but didn't publish my detailed comments
yet. Here are some of my general thoughts:

1. I agree with [~ram_krish] that we should exclude CellChunkMap implementation from this
patch. This patch is big enough and we have here enough design and implementation details.
So we should better concentrate on making just this in a great way. My only concern is that
if we remove the CellChunkMap we have less abilities to test the new code. We should make
sure the new code is well tested. Please add the new tests for all the relevant interfaces
(getChunkId() from any cell, translate chunk ID into chunk, etc.).

2. I disagree with the design decision of putting MemStoreLABChunkCreator to be part of MemStoreChunkPool.
I also don't understand why MemStoreLABChunkCreator works only with chunks allocated from
pool. Please decouple the ChunkPool and the ChunkCreator, there can be chunks without pool,
so there should exist ChunkCreator even if it was decided not to allocate/de-allocate Chunks
via Pool. Whether it is reasonable or not to have chunks without pool is a separate question
and a matter of usage. As we are not sure how exactly CellChunkMap is going to be used in
the future we should not block any option for now. As I have already said, the ChunkCreator
should be responsible for ANY chunk allocation and ANY chunk should have its ID. Maybe it
makes sense to do some small design document?

Now I am going to publish more detailed comments on the RB itself. [~ram_krish], thanks once

> 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: 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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