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From "Andy Jefferson (JIRA)" <j...@apache.org>
Subject [jira] Commented: (JDO-623) Query cancel and timeout support
Date Thu, 19 Mar 2009 11:09:50 GMT

    [ https://issues.apache.org/jira/browse/JDO-623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12683428#action_12683428

Andy Jefferson commented on JDO-623:

Suggested spec updates :-
Add "Query Timeout" (bold heading)
If the query timeout is specified the implementation will use the supplied value as a timeout
for any queries where the underlying datastore supports it. The timeout is in milliseconds.
If it is not specified then the implementation won't set any timeout (unless specified on
a query-by-query basis). 


"Timeout/Cancel" (bold heading)
void setTimeoutMillis(int interval);
This method sets the timeout for this query (in milliseconds) where the underlying datastore
supports it. If the datastore doesn't support timeouts then a JDOQueryTimeoutException is
thrown. This overrides the PersistenceManagerFactory property value (see 11.1)

void cancel();
This method allows the current query to be cancelled (if executing). If the implementation
does not support this operation (maybe due to lack of support in the underlying datastore)
then JDOUnsupportedOptionException is thrown.

> Query cancel and timeout support
> --------------------------------
>                 Key: JDO-623
>                 URL: https://issues.apache.org/jira/browse/JDO-623
>             Project: JDO
>          Issue Type: New Feature
>          Components: api2, tck2
>            Reporter: Andy Jefferson
>            Assignee: Andy Jefferson
>             Fix For: JDO 2 maintenance release 3
>         Attachments: query_timeout.patch
> JDO doesn't have a mechanism to stop queries from overrunning. JPA2 now allows 
> a persistence property to allow timing them out, and most JDO implementations 
> have allowed this as an extension since JDO1. It would make sense for JDO 
> (2.3) to have the same or a variation. I propose having the following
> Simple PMF property "javax.jdo.option.queryTimeout" to specify the number of millisecs
(or secs) before any query is timed out. Throw a QueryTimeoutException (extends JDOException)
when the timeout happens.
> Add methods Query.setTimeout(int), Query.getTimeout() to allow setting/retrieving the
timeout interval on a per-query basis.
> Add method Query.cancel() to cancel any running query. If an implementation doesn't support
cancelling of queries then it should throw a JDOUnsupportedOptionException. Any query execute()
that is cancelled will throw a QueryInterruptedException (extends JDOUserException).

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