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https://issues.apache.org/jira/browse/HBASE-3787?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13659164#comment-13659164
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Andrew Purtell commented on HBASE-3787:
---------------------------------------

There are tough issues here and I haven't thought them through nearly as much 
as Sergey. My advice nonetheless is to be as simple as possible and focus on 
the core problem: We don't want clients to accidentally (from their 
perspective) submit and execute a non idempotent op more than once. Having a 
nonce capability in our RPC that handles all of the corner cases would be 
awesome but that wide scope strikes me as follow on work after solving the 
immediate issue at hand? If the client gets a failure (even if more often and 
if a region moves normally) instead of an accidentally duplicated non 
idempotent op, we have made progress. 
                
> Increment is non-idempotent but client retries RPC
> --------------------------------------------------
>
>                 Key: HBASE-3787
>                 URL: https://issues.apache.org/jira/browse/HBASE-3787
>             Project: HBase
>          Issue Type: Bug
>          Components: Client
>    Affects Versions: 0.94.4, 0.95.2
>            Reporter: dhruba borthakur
>            Assignee: Sergey Shelukhin
>            Priority: Critical
>             Fix For: 0.95.1
>
>         Attachments: HBASE-3787-partial.patch, HBASE-3787-v0.patch, 
> HBASE-3787-v1.patch, HBASE-3787-v2.patch, HBASE-3787-v3.patch, 
> HBASE-3787-v4.patch, HBASE-3787-v5.patch, HBASE-3787-v5.patch
>
>
> The HTable.increment() operation is non-idempotent. The client retries the 
> increment RPC a few times (as specified by configuration) before throwing an 
> error to the application. This makes it possible that the same increment call 
> be applied twice at the server.
> For increment operations, is it better to use 
> HConnectionManager.getRegionServerWithoutRetries()? Another  option would be 
> to enhance the IPC module to make the RPC server correctly identify if the 
> RPC is a retry attempt and handle accordingly.

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