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From "Jingcheng Du (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-17161) MOB : Make ref cell creation more efficient
Date Thu, 01 Dec 2016 11:36:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-17161?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15711733#comment-15711733

Jingcheng Du commented on HBASE-17161:

Thanks Ram. For a mob cell, I think it is important.
In each scan of a mob-enabled cf, we try to read the ref tag. So it helps if the ref tag is
in the first one.

> MOB : Make ref cell creation more efficient
> -------------------------------------------
>                 Key: HBASE-17161
>                 URL: https://issues.apache.org/jira/browse/HBASE-17161
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Anoop Sam John
>            Assignee: Anoop Sam John
>             Fix For: 2.0.0
>         Attachments: HBASE-17161.patch, HBASE-17161.patch
> When we flush MOB data, ref cells are created per actual MOB cell. This creates lots
of garbage
> Refer MobUtils#createMobRefCell
> We need to add 2 tags into the ref cell. An ArrayList is created with default size creating
ref array. Call to CellUtil.getTags will create a new ArrayList even if the original cell
is having no tags.
> A new KV is created which will create a new backing byte[] and do copy.  Also along with
each of the flush/compaction op, a fresh Tag object is created for TableName tag.
> Fixes include
> 1. A table name tag is not going to change per HStore.  Even both the new tags to be
added.  Will keep a byte[] of these 2 tags at MobHStore level so that all flush and compactions
in this store can use it.
> 2. Create a new MobRefCell just like TagRewriteCell where only value and tags part will
be diff from the original cell.

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