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https://issues.apache.org/jira/browse/HBASE-7721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13569405#comment-13569405
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Enis Soztutar commented on HBASE-7721:
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bq. Could punt on this a while given .META. does not split currently (We should
allow it split one day to spread the load and to make it so less damage done if
only a piece of .META. is offline because of server crash rather than all).
Agreed. It means we do not actually need a split policy for now. In HBASE-7748,
I added a delimited key prefix split policy, which can be deployed in META
table.
Do you remember why we have disabled META splits in the first place?
bq. Why you say this Enis?
Just to list our options. If we move to ZK in META, we don't need this issue.
However, that discussion is out of scope for this issue I guess.
> Local Transactions in META
> --------------------------
>
> Key: HBASE-7721
> URL: https://issues.apache.org/jira/browse/HBASE-7721
> Project: HBase
> Issue Type: Improvement
> Components: Coprocessors, regionserver
> Reporter: Enis Soztutar
> Assignee: Enis Soztutar
> Fix For: 0.96.0
>
>
> Thanks to Lars' local transactions patch (HBASE-5229), we can entertain the
> possibility of doing local transactions within META regions.
> We need this mainly for region splits and merges. Clients scan the META
> concurrent to the split/merge operations, and to prevent the clients from
> seeing overlapping region boundaries or holes in META, we just through hoops.
> For more backgroun, see BlockingMetaScannerVisitor, HBASE-5986, and my
> comments at https://reviews.apache.org/r/8716/.
> Now, for the actual implementation options:
> 1. As outlined in http://hadoop-hbase.blogspot.com/2012_02_01_archive.html,
> - We have to implement a Custom RegionSplitPolicy for the META regions to
> ensure that a table's regions are always co-located in the same META region.
> Then we can add MultiRowMutationEndpoint as a system level coprocessor, and
> use it for META operations.
> 2. Do smt like HBASE-7716, and expose local atomic multi-row operations as a
> native API.
> 3. Move META to zookeeper. Use zookeeper.multi.
> Then we can change region split / merge logic to make use of atomic META
> operations.
> Thoughts, suggestions?
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