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https://issues.apache.org/jira/browse/JENA-2020?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17256650#comment-17256650
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Martin Pekár commented on JENA-2020:
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{{I tried consuming the iterator and disregarding the value of .next(). I
returned the consumed iterator, but still the same result.}}
{{The OpExistence operator chooses a triple in a BGP that contains at most two
variables. It then finds a subset of triples in the BGP that have the same
variables that can cover the variables in the chosen triple. The operator must
then use the computed values of the variables in the covering triples in the
BGP and substitute the chosen triple with these values. If the chosen triple
then is concrete, then I assume it exists. So yes, it's related to FILTER
EXISTS.}}
> Purpose of EvaluatorSimple and OpExecutor
> -----------------------------------------
>
> Key: JENA-2020
> URL: https://issues.apache.org/jira/browse/JENA-2020
> Project: Apache Jena
> Issue Type: Question
> Components: ARQ
> Reporter: Martin Pekár
> Priority: Major
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> I am in the midst of adding a new operator in the transformation of OpBGP. I
> am now trying to implement the execution of the operator in the query plan,
> but I am now slightly confused about the purpose of EvaluatorSimple used in
> EvaluatorDispatch and OpExecutor. At the moment, it seems like they are doing
> the same thing. The difference seems to be that OpExecutor stores the result
> of applying the operator in a QueryIterator, whereas EvaluatorSimple stores
> its result in a Table of bindings.
> Can someone give me an explanation of purposes of these two classes and how
> they should be used?
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