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

[Anatoly Polinsky (JIRA)]

ProcessInstancesWaitingForEvent Query is Extremely Inefficient Should Be Simplified
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                 Key: JBRULES-2732
                 URL: https://jira.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


"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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