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https://issues.apache.org/jira/browse/HBASE-11339?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14118911#comment-14118911
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Jonathan Hsieh commented on HBASE-11339:
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bq. Related, the MOB design also attempts to avoid write amplification of large
cells during compaction, by segregating large values into separate files set
outside the normal compaction process. Rather than normal compaction, an
external MapReduce based tool is used for compacting MOB files. HBase has never
required MapReduce before and we should really think hard before introducing
such a change. Are we sure the desired objectives cannot be met with a
pluggable compaction policy?
Removing the external processes that perform "mob compaction" is one of the
follow up goals and is noted at HBASE-11861. We want to get rid of the MR
dependencies because it introduces a new piece of operational complexity and I
don't want that. I don't consider the MOB feature to be production ready if it
still requires the external process to manage this.
The mob feature like other features that require external tooling be
experimental until simplified operationally. We've done this before -- for
example,, I call favored nodes HBASE-7932 experimental becuase it is not
"set-it-and-forget"; it requires extra processes such as an external balancer.
For MOB, after we get the other blockers in (snapshot support, metrics) we'll
revamp the mob compaction and then remove the experimental tag. My goal would
be to get this all in by the end of the year.
> HBase MOB
> ---------
>
> Key: HBASE-11339
> URL: https://issues.apache.org/jira/browse/HBASE-11339
> Project: HBase
> Issue Type: Umbrella
> Components: regionserver, Scanners
> Reporter: Jingcheng Du
> Assignee: Jingcheng Du
> Attachments: HBase MOB Design-v2.pdf, HBase MOB Design-v3.pdf, HBase
> MOB Design-v4.pdf, HBase MOB Design.pdf, MOB user guide.docx, MOB user
> guide_v2.docx, hbase-11339-in-dev.patch
>
>
> It's quite useful to save the medium binary data like images, documents
> into Apache HBase. Unfortunately directly saving the binary MOB(medium
> object) to HBase leads to a worse performance since the frequent split and
> compaction.
> In this design, the MOB data are stored in an more efficient way, which
> keeps a high write/read performance and guarantees the data consistency in
> Apache HBase.
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