Gremlin遍历膨胀(OLTP)

Question

虽然我理解Bulking的原理，但我很想知道从编程的角度来看，机器是如何实现这一点的。如何检测多个遍历器在同一节点上，以决定合并和批量它们。是否有任何用于检测特定情况需要批量的算法的描述。

另外，什么是触发批量的显式步骤。是否有任何指令可以添加到遍历中，以显式地执行批量操作？

Answer 1

批量操作通常与barrier()步骤有关，在TinkerPop的参考文档here中有一些讨论。大多数人不会在他们的Gremlin写作中直接使用barrier() (尽管你可以)，因为TinkerPop中内置的各种遍历策略(比如LazyBarrierStrategy )试图自动将它们注入到遍历中，而这些遍历策略可能会起到一些作用。

您可以通过在遍历过程中执行explain()来查看barrier()步骤被注入的位置/时间：

gremlin> g.V().out().both().explain()
==>Traversal Explanation
=======================================================================================================================================
Original Traversal                 [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]

ConnectiveStrategy           [D]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
IncidentToAdjacentStrategy   [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
MatchPredicateStrategy       [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
RepeatUnrollStrategy         [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
PathRetractionStrategy       [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
FilterRankingStrategy        [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
InlineFilterStrategy         [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
AdjacentToIncidentStrategy   [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
CountStrategy                [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), VertexStep(BOTH,vertex)]
LazyBarrierStrategy          [O]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), NoOpBarrierStep(2500), VertexStep(BOTH,vertex)]
TinkerGraphCountStrategy     [P]   [GraphStep(vertex,[]), VertexStep(OUT,vertex), NoOpBarrierStep(2500), VertexStep(BOTH,vertex)]
TinkerGraphStepStrategy      [P]   [TinkerGraphStep(vertex,[]), VertexStep(OUT,vertex), NoOpBarrierStep(2500), VertexStep(BOTH,vertex)]
ProfileStrategy              [F]   [TinkerGraphStep(vertex,[]), VertexStep(OUT,vertex), NoOpBarrierStep(2500), VertexStep(BOTH,vertex)]
StandardVerificationStrategy [V]   [TinkerGraphStep(vertex,[]), VertexStep(OUT,vertex), NoOpBarrierStep(2500), VertexStep(BOTH,vertex)]

Final Traversal                    [TinkerGraphStep(vertex,[]), VertexStep(OUT,vertex), NoOpBarrierStep(2500), VertexStep(BOTH,vertex)]

Answer 2

在这里，在上面的@stephen评论之后，我只想分享一个博客的链接，该博客深入解释了著名的LazyBarrierStrategy