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From "Ted Yu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7857) Sub-region management
Date Sat, 16 Feb 2013 06:31:14 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7857?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13579731#comment-13579731
] 

Ted Yu commented on HBASE-7857:
-------------------------------

Subregion is hardly a new idea. I am open to other terms (arena, section, etc).

Subregions divide the key space of a region into (potentially variable-width) non-overlapping
segments.
In terms of compaction, subregions map to stripes.

In terms of memstore, there can be counterpart to stripes.
Matt Corgan proposed (see HBASE-3484) memstore be represented as Set<Set<KeyValue>>.
Another possibility is to use List<Set<KeyValue>> for memstore. The goal is the
same: flushing doesn't produce L0 files (that have all the keys in the region). Each subregion
flushes into corresponding stripe of store files.
Some index would facilitate quick lookup of subregion in the collection of Set<KeyValue>.

Refactoring of memstore would be done first to make subregion pluggable.

Will continue to think through this topic.
                
> Sub-region management
> ---------------------
>
>                 Key: HBASE-7857
>                 URL: https://issues.apache.org/jira/browse/HBASE-7857
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Ted Yu
>
> Sub-region provides a light weight management below region level.
> Matt Corgan has a nice summary of the relationship between region size and number of
regions on region server:
> https://issues.apache.org/jira/browse/HBASE-7667?focusedCommentId=13575024&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13575024
> HBASE-7667 proposed stripe compaction. However, to fully achieve fine-grained management,
more components should participate:
> * memstore flush should ideally have knowledge about what makes stripe compaction work
efficiently
> * we need to figure out where to store sub-region boundary information so that components
have easy access. Boundary information should sustain after region moves from one server to
another.
> Since HBASE-7667 focuses on compaction aspect, this JIRA discusses sub-region management
in other components so that we better understand the benefits and complexities.
> User may want to see how sub-regions are shaped on web UI.

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