[jira] [Commented] (JENA-382) SPARQL Updates are not cancelable

["Rob Vesse (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13634192#comment-13634192 ] 

Rob Vesse commented on JENA-382:
--------------------------------

NB - There is currently no branch as it was obsoleted by Stephen's streaming update changes and the design needs rethinking

Needs to consider the following:
- Cancellation for streaming vs non-streaming update engines
- Leveraging existing query cancellation if an update is stuck in the query portion of a DELETE/INSERT
- Interaction with transaction mechanisms -> cancellation should almost certainly render a transaction as un-committable and require a rollback
                
> SPARQL Updates are not cancelable
> ---------------------------------
>
>                 Key: JENA-382
>                 URL: https://issues.apache.org/jira/browse/JENA-382
>             Project: Apache Jena
>          Issue Type: Improvement
>          Components: ARQ
>            Reporter: Rob Vesse
>            Assignee: Rob Vesse
>              Labels: cancellation, gsoc2013, sparql, transactions, update
>   Original Estimate: 336h
>  Remaining Estimate: 336h
>
> Currently queries are cancelable but updates are not.  Updates are just of capable of running awry especially since some of them can embed queries within them.  In general any update that generates a large amount of data can result in a long running update.
> Therefore we should make it possible to cancel updates, my rough proposal for this is as follows:
> 1 - Provide a cancel() method on UpdateProcessor
> 2 - Provide a cancel() method on individual update commands so a processor can cancel() whichever is currently running
> When updates are cancelled it must be treated as if updates failed and the transaction should be rolled back or marked as uncommittable as appropriate.
> I will create a SVN branch to experiment on this feature.

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