[ https://issues.apache.org/jira/browse/JENA-2020?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17255226#comment-17255226 ]
Andy Seaborne commented on JENA-2020: ------------------------------------- Only one per execution - which is determined by {{QueryEngineFactory}} and {{QueryEngineRegistry}}. Not sure what you mean by "before" here. The {{QueryIterator}} passed into an evaluation step is the previous stage if it is part of an {{OpSequence}} or {{OpDisjunction}} otherwise it is step below in the execution tree (see, for example, {{OpJoin}}). > 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? -- This message was sent by Atlassian Jira (v8.3.4#803005)