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https://issues.apache.org/jira/browse/TINKERPOP3-779?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14650484#comment-14650484
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ASF GitHub Bot commented on TINKERPOP3-779:
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Github user okram commented on the pull request:
https://github.com/apache/incubator-tinkerpop/pull/91#issuecomment-126942879
The problem with OLAP (global children) is that you can't do stuff like (as
you say) "first successful child" as everything is executing in parallel and
you don't know for which input what child output you are referring too. I
suspect you could get fancy with path analysis, but then bulking goes away.
We really need to make it so that global and local children behave "the
same" as there are other steps that currently can't work in OLAP (e.g.
`intersect()`, etc.).
> coalesce should not forget path
> -------------------------------
>
> Key: TINKERPOP3-779
> URL: https://issues.apache.org/jira/browse/TINKERPOP3-779
> Project: TinkerPop 3
> Issue Type: Bug
> Components: process
> Affects Versions: 3.0.0-incubating
> Reporter: Matt Frantz
> Assignee: Matt Frantz
>
> It seems like the path along whichever branch of the {{coalesce}} step should
> be preserved downstream. In 3.0.0, this is not the case:
> {noformat}
> gremlin> g.V().out().out().path()
> ==>[v[1], v[4], v[5]]
> ==>[v[1], v[4], v[3]]
> gremlin> g.V().coalesce(out().out()).path()
> ==>[v[1], v[5]]
> ==>[v[1], v[3]]
> {noformat}
> I would expect the output of the second statement to equal the first.
> Also, to be clear, the path should reflect whichever of the traversal
> arguments to {{coalesce}} were productive.
> {noformat}
> gremlin> g.V().out().out().path()
> ==>[v[1], v[4], v[5]]
> ==>[v[1], v[4], v[3]]
> gremlin> g.V().coalesce(out().out().out(), out().out()).path()
> ==>[v[1], v[5]]
> ==>[v[1], v[3]]
> {noformat}
> Again, I would expect the output of the second statement to equal the first.
> The path truncation behavior would be nice to preserve in the proposed
> {{sub}} step (TINKERPOP3-716).
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