Edge traveresal .hasId() not returning expected results
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AC
Thanks Boxuan! I look forward to that release. In the meantime, I was able to work around this issue now that I know it is not producing the expected results, in a way that should be compatible with this change once it is rolled out. I really appreciate your thorough answer and explanation. On Sat, Nov 6, 2021 at 5:12 PM Boxuan Li <liboxuan@...> wrote: Fixed by https://github.com/JanusGraph/janusgraph/pull/2849 and will be included in the next release (0.6.1). |
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Boxuan Li
Fixed by https://github.com/JanusGraph/janusgraph/pull/2849 and will be included in the next release (0.6.1).
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Boxuan Li
Hi Adam,
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Thanks for reporting! This is a bug and I just created an issue for it: https://github.com/JanusGraph/janusgraph/issues/2848 If you wanted to know more about this bug, feel free to post a follow-up on that issue. JanusGraphStep is an implementation of TinkerPop GraphStep which contains some optimization. JanusGraph converts GraphStep to JanusGraphStep as long as it finds there is space to optimize. In the “g.E().hasId(xx)” example, if we strictly follow the execution order, JanusGraph would load all edges and then do an in-memory filtering. That’s where `JanusGraphStep` comes into play - it “folds” all `has` conditions (including `hasId` step) so that index can be potentially utilized. Unfortunately, due to a bug that you found, g.E().hasId(xx) does not work as expected. If you insert a dummy `map` step in-between like this: g.E().map{t -> t.get()}.hasId(“4r6-39s-69zp-3c8”) Then you will get the result you want. However, this is highly discouraged, as it will aggressively prevent JanusGraph from doing any optimization, and requires a full scan on all data entries. Best regards, Boxuan
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AC
Hey folks, I'm seeing strange results trying to use the hasId step on an edge traversal: @ g.E("4r6-39s-69zp-3c8").toList res49: List[Edge] = List(e[4r6-39s-69zp-3c8][4240-RetrocomputerPurchaser->4328]) @ g.E().hasId("4r6-39s-69zp-3c8").toList res50: List[Edge] = List() @ g.E("4r6-39s-69zp-3c8").traversal.profile().toList res51: java.util.List[org.apache.tinkerpop.gremlin.process.traversal.util.TraversalMetrics] = [Traversal Metrics Step Count Traversers Time (ms) % Dur ============================================================================================================= GraphStep(edge,[4r6-39s-69zp-3c8]) 1 1 0.237 100.00 >TOTAL - - 0.237 -] @ g.E().hasId("4r6-39s-69zp-3c8").traversal.profile().toList res52: java.util.List[org.apache.tinkerpop.gremlin.process.traversal.util.TraversalMetrics] = [Traversal Metrics Step Count Traversers Time (ms) % Dur ============================================================================================================= JanusGraphStep(edge,[4r6-39s-69zp-3c8]) 0.039 100.00 >TOTAL - - 0.039 -] 1) Why would these two traversals produce different results? 2) What's the difference between the GraphStep and JanusGraphStep representations of these traversals? They look the same otherwise via explain/profile. 3) Is there any working encoding of this query starting with an edge traversal g.E() that can produce the same result? Thanks, - Adam |
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