[jboss-jira] [JBoss JIRA] Commented: (JBRULES-2732) ProcessInstancesWaitingForEvent Query is Extremely Inefficient and Should Be Simplified

[Bostjan Dolenc (JIRA)]

    [ https://issues.jboss.org/browse/JBRULES-2732?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12573219#comment-12573219 ] 

Bostjan Dolenc commented on JBRULES-2732:
-----------------------------------------

I've had to implemented this change myself as SQL was not property generated for this query when running on Oracle. I probably could contribute it for inclusion in the trunk, but it's very trivial change anyway.

> ProcessInstancesWaitingForEvent Query is Extremely Inefficient and Should Be Simplified
> ---------------------------------------------------------------------------------------
>
>                 Key: JBRULES-2732
>                 URL: https://issues.jboss.org/browse/JBRULES-2732
>             Project: Drools
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: All
>    Affects Versions: 5.1.1.FINAL
>         Environment: N/A
>            Reporter: Anatoly Polinsky
>            Assignee: Mark Proctor
>              Labels: drools, drools-flow, persistence
>   Original Estimate: 2 hours
>  Remaining Estimate: 2 hours
>
> "ProcessInstancesWaitingForEvent" query that is used after each process / subprocess ends is extremely inefficient, and since there is no way to force an INDEX without being coupled with JPA provider, this query execution time increase exponentially as the number of processes goes up. Currently with only 20000 processes, the query takes 18(!!!) seconds to execute:
> <named-query name="ProcessInstancesWaitingForEvent">
>     <query>
>         SELECT processInstanceInfo.processInstanceId
>         FROM ProcessInstanceInfo processInstanceInfo
>         WHERE :type in elements ( processInstanceInfo.eventTypes )
>     </query>
> </named-query> 
> It is inefficient not only because there is no INDEX enforced, but because it goes into the sub query for no good reason. The better/correct query is:
> SELECT processInstanceInfo.processInstanceId
> FROM ProcessInstanceInfo processInstanceInfo, EventTypes eventTypes
> WHERE eventTypes.element = :type
> AND processInstanceInfo.processInstanceId = eventTypes.processInstanceId 
> In order to get to this "better" query, since it is a JPA one, an EventType/s entity should be created ( it does not currently exist in 5.1.1 ).
> /Anatoly

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