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https://issues.apache.org/jira/browse/HBASE-18042?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16011284#comment-16011284
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Andrew Purtell commented on HBASE-18042:
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We are not supposed to break wire compatibility in minor versions. This is 
arguable. The protobuf change is compatible in the strictest sense in that 
mismatched versions can still parse messages. The fact that semantics rely on a 
new field not present in older versions means not really. 

> 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
>    Affects Versions: 1.3.1
>            Reporter: Karan Mehta
>            Assignee: Karan Mehta
>
> 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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