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From "Mingjie Lai (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-3583) Coprocessors: RegionObserver: ScannerNext and ScannerClose hooks are called when get() is invoked
Date Thu, 17 Mar 2011 00:16:29 GMT

    [ https://issues.apache.org/jira/browse/HBASE-3583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13007753#comment-13007753
] 

Mingjie Lai commented on HBASE-3583:
------------------------------------

For option 2, the impact would be wide, since client also uses the same scanner id. 

Option 3 is not feasible since changing the Map type would require changing the return type
for HRegion.getScanner(). Sorry about it.  

> Coprocessors: RegionObserver: ScannerNext and ScannerClose hooks are called when get()
is invoked
> -------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-3583
>                 URL: https://issues.apache.org/jira/browse/HBASE-3583
>             Project: HBase
>          Issue Type: Bug
>          Components: coprocessors
>    Affects Versions: 0.92.0
>            Reporter: Mingjie Lai
>            Assignee: Mingjie Lai
>             Fix For: 0.92.0
>
>         Attachments: HBase3583.patch
>
>
> RegionObserver upcalls are expected to be triggered by corresponding client calls. 
> I found that if a HTable.get() is issued, ScannerNext, and ScannerClose hooks are also
invoked. 
> Here is the reason: HRegion.get() is implemented with an internal scanner:
> {code}
>     InternalScanner scanner = null;
>     try {
>       scanner = getScanner(scan);
>       scanner.next(results);
>     } finally {
>       if (scanner != null)
>         scanner.close();
>     }
> {code}
> where scanner.next, and scanner.close() are implemented with RegionObserver hooks. 

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