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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16838) Implement scan
Date Mon, 24 Oct 2016 19:48:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15603006#comment-15603006
] 

stack commented on HBASE-16838:
-------------------------------

bq. The reason why we introduce a small scan is that we want to get the whole result with
one rpc call, so I think it is reasonable to have the same API with get?

That seems reasonable. Just seems weird having two ways to do a Scan, one way when small and
another when not-small. The method should be called smallScan? Or do you think that the the
API with a return that is a CompletableFuture is indicator enough that this is a short-lived
Scan?  Maybe it is.

bq. So I think a scan method that returns the whole results is acceptable? 

You mean a whole region's worth of results or you mean the batch? If the former, no, we should
not return whole regions' worth (I don't think you meant this) and if the latter, where is
the user getting an Async API? They have to block even though the Scan maybe returning them
chunks of the Scan or later, we could be streaming Cells back to the API. CompleteableFuture
is all or nothing with its Done? There is no way to get out Cell at a time? Is that a different
API?

On AsyncResultScanner, https://github.com/jurmous/async-hbase-client/blob/master/src/main/java/org/apache/hadoop/hbase/client/AsyncResultScanner.java,
there is a use case where you'd want to perhaps prefetch or do parallel non-sequenced access
to a Scan but that'd be tough since we don't know where the next 'next' should start till
the currently running one has returned. Thanks for turning up AsyncResultScanner. I don't
think it applicable given where we are now after changes you've done [~Apache9]



> Implement scan
> --------------
>
>                 Key: HBASE-16838
>                 URL: https://issues.apache.org/jira/browse/HBASE-16838
>             Project: HBase
>          Issue Type: Sub-task
>    Affects Versions: 2.0.0
>            Reporter: Duo Zhang
>            Assignee: Duo Zhang
>             Fix For: 2.0.0
>
>         Attachments: HBASE-16838.patch
>
>




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