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https://issues.apache.org/jira/browse/HBASE-6696?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13458118#comment-13458118
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James Ji commented on HBASE-6696:
---------------------------------

[~andrew.purt...@gmail.com]
May I know how is the status of this issue? Are you gonna fix it in the next 
release? 
You answer will be appreciated. 
                
> Add CP hooks pre and post split transaction point-of-no-return
> --------------------------------------------------------------
>
>                 Key: HBASE-6696
>                 URL: https://issues.apache.org/jira/browse/HBASE-6696
>             Project: HBase
>          Issue Type: Improvement
>          Components: coprocessors, regionserver
>    Affects Versions: 0.96.0, 0.94.2
>            Reporter: Andrew Purtell
>            Assignee: Andrew Purtell
>
> In the discussion "Improving Coprocessor postSplit/postOpen synchronization" 
> on user@hbase, a user implementing a secondary indexing scheme writes in:
> {quote}
> The goal with splits is to create two new daughter regions with the
> corresponding splits of the secondary indexes and lock these regions such
> that Puts/Deletes that occur while postSplit is in progress will be queued
> up so we don't run into consistency issues. [...] As of right now, the HBase 
> coprocessors do not easily support a way to achieve this level of consistency 
> in that there is no way to distinguish a region being opened from a split or 
> a regular open.
> {quote}
> Setting aside the particulars of the use case, the issue is the {{preSplit}} 
> hook does not provide the identities of the daughter regions (they don't 
> exist yet) and the {{postSplit}} hook, while providing the identities of the 
> daughter regions, runs after the master has processed the split and the 
> daughters are already opened or opening. A CP implementer has no interception 
> point available where the daughters exist but are not yet open.
> This JIRA proposes to add two new CP hooks to just before and after the 
> point-of-no-return (PONR) in the split transaction: {{preSplitPONR}} and 
> {{postSplitPONR}}. Perhaps the naming can be improved. This will address the 
> above use case but additionally support overloading of the split transaction 
> itself. We also need to address observer notification if the split 
> transaction fails. This is like HBASE-5827 but scoped to this specific 
> consideration only.

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