[jira] [Commented] (CALCITE-4432) When the RelNode's input is the same subset as the node belonged to, not choose this node as best.

[Julian Hyde (Jira)]

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https://issues.apache.org/jira/browse/CALCITE-4432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17247585#comment-17247585
 ] 

Julian Hyde commented on CALCITE-4432:
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I'm curious: what was the resolution here?

I agree that cyclic graphs are a problem. [~FatLittle]'s suggestion to use the 
cost model often works, but not always (e.g. if the arc adds no cost). So, I'd 
like to come up with a general-purpose way to deal with cyclic graphs. Any 
ideas will help.

> When the RelNode's input is the same subset as the node belonged to, not 
> choose this node as best.
> --------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-4432
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4432
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Ziwei Liu
>            Assignee: Ziwei Liu
>            Priority: Major
>
> If a subset have a cyclic node, the node's input is this subset itself. If 
> the beset 



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