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https://issues.apache.org/jira/browse/HBASE-10576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13978998#comment-13978998
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Jeffrey Zhong commented on HBASE-10576:
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Thanks for all the very good comments & feedbacks. I think the most doubts come
from "no meta entries for shadow regions".
We can create meta entries for shadow regions but with "shadow" state(like
disable state) so that AM & Balancer can skip them. With entries in META table,
I think most questions are answered. As [~ram_krish] suggested above, there
will be some tweaks in coprocessor hook & region open code in order to open a
region from coprocessor.
{quote}
it conflicts with that we only want the master to handle region
assignments/recovery
{quote}
There is no conflict because the shadow region location is pre-determined by
its data region.
My original thought without meta entries for shadow regions is a coprocessors
intensive approach as following.
For creating local-index tables, we reopen data table(through enable/disable
table). During data table region opening, we can create index regions under
same data region directory if not present or open index regions if already
exists.
For index table access, we can use coprocessor preScannerOpen() to intercept
scan if the passed in scan has attribute(or hint) using index OR tweak hbase
client to be aware of shadowing regions in terms of location finding.
> Custom load balancer to co-locate the regions of two tables which are having
> same split keys
> --------------------------------------------------------------------------------------------
>
> Key: HBASE-10576
> URL: https://issues.apache.org/jira/browse/HBASE-10576
> Project: HBase
> Issue Type: Sub-task
> Components: Balancer
> Reporter: rajeshbabu
> Assignee: rajeshbabu
> Attachments: HBASE-10536_v2.patch, HBASE-10576.patch
>
>
> To support local indexing both user table and index table should have same
> split keys. This issue to provide custom balancer to colocate the regions of
> two tables which are having same split keys.
> This helps in Phoenix as well.
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