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https://issues.apache.org/jira/browse/HBASE-18042?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16022463#comment-16022463
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Duo Zhang commented on HBASE-18042:
-----------------------------------

The patch worked in our internal version. Let me prepare patches for branch-1 
and branch-1.3.

> Client Compatibility breaks between versions 1.2 and 1.3
> --------------------------------------------------------
>
>                 Key: HBASE-18042
>                 URL: https://issues.apache.org/jira/browse/HBASE-18042
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver, scan
>    Affects Versions: 2.0.0, 1.4.0, 1.3.1
>            Reporter: Karan Mehta
>            Assignee: Duo Zhang
>            Priority: Critical
>             Fix For: 2.0.0, 1.4.0, 1.3.2
>
>         Attachments: HBASE-18042.patch
>
>
> OpenTSDB uses AsyncHBase as its client, rather than using the traditional 
> HBase Client. From version 1.2 to 1.3, the {{ClientProtos}} have been 
> changed. Newer fields are added to {{ScanResponse}} proto.
> For a typical Scan request in 1.2, would require caller to make an 
> OpenScanner Request, GetNextRows Request and a CloseScanner Request, based on 
> {{more_rows}} boolean field in the {{ScanResponse}} proto.
> However, from 1.3, new parameter {{more_results_in_region}} was added, which 
> limits the results per region. Therefore the client has to now manage sending 
> all the requests for each region. Further more, if the results are exhausted 
> from a particular region, the {{ScanResponse}} will set 
> {{more_results_in_region}} to false, but {{more_results}} can still be true. 
> Whenever the former is set to false, the {{RegionScanner}} will also be 
> closed. 
> OpenTSDB makes an OpenScanner Request and receives all its results in the 
> first {{ScanResponse}} itself, thus creating a condition as described in 
> above paragraph. Since {{more_rows}} is true, it will proceed to send next 
> request at which point the {{RSRpcServices}} will throw 
> {{UnknownScannerException}}. The protobuf client compatibility is maintained 
> but expected behavior is modified.



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