[jira] [Updated] (HBASE-6696) Add CP hooks pre and post split transaction point-of-no-return

["Andrew Purtell (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-6696?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrew Purtell updated HBASE-6696:
----------------------------------

    Assignee:     (was: Andrew Purtell)

> 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: 0.94.2, 0.95.2
>            Reporter: 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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