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From "Duo Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-17045) Unify the implementation of small scan and regular scan
Date Tue, 10 Jan 2017 06:39:58 GMT

     [ https://issues.apache.org/jira/browse/HBASE-17045?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Duo Zhang updated HBASE-17045:
    Attachment: HBASE-17045.patch

Add a limit option to Scan which means the limit of rows for this scan operation.

RS will close the scanner and set moreResults to false when the number of rows reaches the
limit. Also did some refactoring when implementing the feature in RSRpcServices.

In AsyncClientScanner, we will also fetch some cells when open scanner.

Remove smallScan methods in AsyncTableBase and remove all small scan related code for asynchronous
implementation. Add a scanAll method.

Deprecated setSmall and isSmall methods for Scan.

> Unify the implementation of small scan and regular scan
> -------------------------------------------------------
>                 Key: HBASE-17045
>                 URL: https://issues.apache.org/jira/browse/HBASE-17045
>             Project: HBase
>          Issue Type: Sub-task
>          Components: Client, scan
>    Affects Versions: 2.0.0, 1.4.0
>            Reporter: Duo Zhang
>             Fix For: 2.0.0
>         Attachments: HBASE-17045.patch
> See [~enis]'s comment in HBASE-16838
> https://issues.apache.org/jira/browse/HBASE-16838?focusedCommentId=15637803&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15637803
> But there is another scenario that we need small scan is that, we do not know the stop
row but we only want a small set of results. For example, in the implementation of region
locator, we will use small scan and set caching to 1 as we only need one row.
> So I think we need to add a new option(maybe called limit?) for the scan object, and
deprecate the small option. And the server side modification should also be committed to branch-1
to simplify the logic of async client in 2.0.

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