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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13333) Renew Scanner Lease without advancing the RegionScanner
Date Sun, 03 May 2015 00:10:06 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13333?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14525558#comment-14525558
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Lars Hofhansl commented on HBASE-13333:
---------------------------------------

Cool... I'll commit to 0.98, 1.x.y first (since I know this is the only way to make it work
there and be 100% backwards compatible).

In trunk, should we make this explicit in the protocol? I.e. add a new bit in PB to indicate
that we would just like to renew the lease?
(as the "client-server-scan-size gate" showed, going by assumption and deriving state from
proxies can be dangerous)


> Renew Scanner Lease without advancing the RegionScanner
> -------------------------------------------------------
>
>                 Key: HBASE-13333
>                 URL: https://issues.apache.org/jira/browse/HBASE-13333
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>             Fix For: 2.0.0, 0.98.13, 1.0.2, 1.1.1
>
>         Attachments: 13333-0.98.txt
>
>
> We have a usecase (for Phoenix) where we want to let the server know that the client
is still around. Like a client-side heartbeat.
> Doing a full heartbeat is complicated, but we could add the ability to make scanner call
with caching set to 0. The server already does the right thing (it renews the lease, but does
not advance the scanner).
> It looks like the client (ScannerCallable) also does the right thing. We cannot break
ResultScanner before HBase 2.0, but we can add a renewLease() method to AbstractClientScaner.
Phoenix (or any other caller) can then cast to ClientScanner and call that method to ensure
we renew the lease on the server.
> It would be a simple and fully backwards compatible change. [~giacomotaylor]
> Comments?



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