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From "David Medinets (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-697) Break Scanner parameterization from Key,Value to Key,{Something}
Date Tue, 24 Jul 2012 21:57:34 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-697?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13421803#comment-13421803
] 

David Medinets commented on ACCUMULO-697:
-----------------------------------------

Thank you. I've used generics before but hadn't explicitly thought about K and V simply being
placeholders.
                
> Break Scanner parameterization from Key,Value to Key,{Something}
> ----------------------------------------------------------------
>
>                 Key: ACCUMULO-697
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-697
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: client
>    Affects Versions: 1.5.0
>            Reporter: Josh Elser
>            Assignee: Josh Elser
>
> When writing a custom iterator, many times the iterator has some semantic knowledge of
what each Key/Value being returned actually means (e.g. A word count could be returning Key/Value
but really is returning an Integer/Long count in the Value). This forces the client to know
what is going to be returned and handle the cast/transformation.
> I believe it should be fairly straightforward to encapsulate this transformation inside
the Accumulo client code. I plan on investigating the possibility of changing the ScannerBase
impl, or perhaps making a TypedScannerBase, in which the iterator at the "top" of the stack
for a scan can return something other than a Value to the client.

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