[jira] [Updated] (HBASE-13984) Add option to allow caller to know the heartbeat and scanner position when scanner timeout

["He Liangliang (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-13984?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

He Liangliang updated HBASE-13984:
----------------------------------
    Release Note: 
Added a scan option to allow the heartbeat visiable to the caller. 
When this option is set true, the client scanner iterator will yield a heartbeat result which contains the next cell when time limit is reached in the server side. In this case, the scanner will only break in the boundary of rows, so the heartbeat result rowkey can be used as the start row in the new scanner to continue the scan.

  was:
Added an explicit heartbeat option in client setting.
When this option is set true and the scan allowPartialResults if false, the client scanner iterator will yield a fake partial row which contains the current scaned position when time limit is reached in the server side. The call need to check whether the returned row is partial in this case.


> Add option to allow caller to know the heartbeat and scanner position when scanner timeout
> ------------------------------------------------------------------------------------------
>
>                 Key: HBASE-13984
>                 URL: https://issues.apache.org/jira/browse/HBASE-13984
>             Project: HBase
>          Issue Type: Improvement
>          Components: Scanners
>            Reporter: He Liangliang
>            Assignee: He Liangliang
>         Attachments: HBASE-13984-V1.diff
>
>
> HBASE-13090 introduced scanner heartbeat. However, there are still some limitations (see HBASE-13215). In some application, for example, an operation access hbase to scan table data, and there is strict limit that this call must return in a fixed interval. At the same time, this call is stateless, so the call must return the next position to continue the scan. This is typical use case for online applications.
> Based on this requirement, some improvements are proposed:
> 1. Allow client set a flag whether pass the heartbeat (a fake row) to the caller (via ResultScanner next)
> 2. Allow the client pass a timeout to the server, which can override the server side default value
> 3. When requested by the client, the server peek the next cell and return to the client in the heartbeat message



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