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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, 27 Mar 2017 08:59:42 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942878#comment-15942878

Anastasia Braginsky commented on HBASE-16438:

OK, I understand what you are saying. Then how about using Java's Soft References in the ChunkCreator?


In short, Soft References are used in Java to implement caches and objects pointed by soft
references can be GCed if no other (hard reference) is pointing to this object. 

This sounds to me as good (and again simple) solution. If any cell is not reachable from any
CSLM/CellArrayMap/CellChunkMap then we are not going to read its chunkID and to ask for translation,
so we do not care that its reference is cleared from the ChunkCreator's map. Just need to
be careful about those null pointers in the ChunkCreator's Map. What do you think?

bq. I mean how to pass the info whether the CSLM has to be converted to CellArrayMap or CellChunkMap.

I plan to have it user-configured as part of MemStore definition (at least as a first step).
I mean once created, some CompactingMemStore is planed to work with CellArayMap and another
CompactingMemStore is created to work with CellChunkMap (mostly for the off-heap). But this
is of course can be changed.

> 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.patch, MemstoreChunkCell_memstoreChunkCreator_oldversion.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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