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Posted to dev@hbase.apache.org by "Marek Srank (JIRA)" <ji...@apache.org> on 2016/05/03 15:42:12 UTC

[jira] [Created] (HBASE-15759) RegionObserver.preStoreScannerOpen() doesn't have acces to current readpoint

Marek Srank created HBASE-15759:
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             Summary: 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


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 lead to bug, when we were incorrectly using smallestReadpoint() instead, which made coprocessor missing data in some cases [1].

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[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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