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From "He Liangliang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13984) Add option to allow caller to know the heartbeat and scanner position when scanner timeout
Date Fri, 03 Jul 2015 14:03:05 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13984?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14613207#comment-14613207
] 

He Liangliang commented on HBASE-13984:
---------------------------------------

[~stack] What is the expected behavior if the user want peek next and also accept partial?
Since the kvs in the store heap and the joint heap are not in sort order, so what should the
next be if the time limit is reached between scanning two heaps? Looks like next cell is applicable
only for non-partial results.

> 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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