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From "Daniel Kuppitz (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (TINKERPOP-1367) Preserve path history for min() and max()
Date Tue, 12 Jul 2016 15:46:20 GMT

    [ https://issues.apache.org/jira/browse/TINKERPOP-1367?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15373107#comment-15373107

Daniel Kuppitz commented on TINKERPOP-1367:

I provided a lambda-free traversal on the mailing list, that does exactly that (emit all max
paths). We can make it work with what we currently have, but it's pretty cumbersome (and memory
intensive). Two separate queries would probably perform better than the single all-in-one
query. Hence, I like the min/max sideEffect proposal. Kinda... It still doesn't look very
intuitive, but much better than what we can currently do.

> Preserve path history for min() and max()
> -----------------------------------------
>                 Key: TINKERPOP-1367
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-1367
>             Project: TinkerPop
>          Issue Type: Improvement
>          Components: process
>    Affects Versions: 3.2.0-incubating
>            Reporter: Jason Plurad
> Via https://groups.google.com/d/msg/gremlin-users/qZwsvRjw7L4/YyT-s1foBAAJ
> {noformat}
> gremlin> g.V().outE().as('e').values('weight').path()
> ==>[v[1], e[9][1-created->3], 0.4]
> ==>[v[1], e[7][1-knows->2], 0.5]
> ==>[v[1], e[8][1-knows->4], 1.0]
> ==>[v[4], e[10][4-created->5], 1.0]
> ==>[v[4], e[11][4-created->3], 0.4]
> ==>[v[6], e[12][6-created->3], 0.2]
> gremlin> g.V().outE().as('e').values('weight').max().path()
> ==>[1.0]
> {noformat}
> Currently all reducing barriers are treated the same (min, max, mean, etc.). But they
are indeed different when it comes to path computations. Some of them could preserve the path
history, others could not.
> For max() and min(), we could preserve the path history. In fact, in this respect, max()
and min() would NOT be ReducingBarrierSteps, but in fact be some sort of "barrier" FilterStep.

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