[jira] [Commented] (JENA-2020) Purpose of EvaluatorSimple and OpExecutor

["Andy Seaborne (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-2020?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17255205#comment-17255205 ] 

Andy Seaborne commented on JENA-2020:
-------------------------------------

ARQ has two separate query evaluators - a simple one, {{EvaluatorSimple}}, (the "ref" engine, {{--engine=ref}} on the command line) that does no smarts and materializes intermediate results. It is (almost) completely separate and is supposed to be simple you can just look at it, inspect the execution (the intermediate results) and be confident it is doing the right thing. It is useful for comparing output from the main engine. They should get the same answers (caveat "reference" does not have all extension features).

{{OpExecutor}} is the execution used normally.

 

 

 

 

 

> 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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