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From "Ted Yu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15759) RegionObserver.preStoreScannerOpen() doesn't have acces to current readpoint
Date Tue, 03 May 2016 13:57:12 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15759?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15268753#comment-15268753
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Ted Yu commented on HBASE-15759:
--------------------------------

I saw Anoop's comment above by which time I already had a tentative patch which is for reference.

> RegionObserver.preStoreScannerOpen() doesn't have acces to current readpoint
> ----------------------------------------------------------------------------
>
>                 Key: HBASE-15759
>                 URL: https://issues.apache.org/jira/browse/HBASE-15759
>             Project: HBase
>          Issue Type: Improvement
>          Components: Coprocessors
>            Reporter: Marek Srank
>            Priority: Minor
>              Labels: coprocessors
>         Attachments: 15759.v1.patch
>
>
> RegionObserver.preStoreScannerOpen() doesn't have acces to current readpoint. This is
crucial e.g. when creating a new StoreScanner.
> Although it is possible to obtain the readpoint via following workaround:
> ((HStore)store).getHRegion().getReadpoint(IsolationLevel.READ_COMMITTED)
> ...it presumes some knowledge of HBase internals and is not a clear option for user.
> The problem was introduced in HBASE-9754, where readpoint was introduced as an argument
to StoreScanner constructor, but wasn't passed to the preStoreScannerOpen() hook in HStore.getScanner().
> In our case it led to bug, when we were incorrectly using smallestReadpoint() instead,
which made coprocessor missing data in some cases [1].
> __________
> [1] http://mail-archives.apache.org/mod_mbox/hbase-dev/201604.mbox/%3CCAOUjMkwptCGacQ0d-4yOinDVBT%2Bbi2NOZee0fSbq%2Bk1R6V4-aw%40mail.gmail.com%3E



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