OrientDB组通过使用图形进行查询 [英] OrientDB group by query using graph

问题描述

我需要对某个类的顶点属性执行分组聚合，然而，group by字段是距离当前节点两步的顶点，我无法使其工作。

我的情况：
顶点A包含我想要聚合的属性，并且有 n 引用。如果顶点具有由边界定义的到顶点F ，那么我想要分组的顶点是这些顶点（B，C或D） 。



  A ----引用 - > B  - 由 - >定义E 
 \ ---参考文献 - > C  - 由 - >定义F 
 \  - 参考文献 - > D  - 由 - >定义G 
 ... 
  

我认为可以使用的查询是：

  select sum（property），groupOn from（
 select property，out（'references'）[out（'definedBy'）。@ rid = F] as groupOn from AClass 
）group by groupOn 
  

但它没有工作，内部声明给了我一个奇怪的回应，这是不正确的（不返回顶点），我怀疑 out（）不支持括号条件（原因对于。@ rid 是我发现的文档声明只支持=。

out（'references'）[out（'definedBy'）contains F] 也不起作用，返回 out（'definedBy'）用于 $ current 顶点）。



任何人有想法如何实现这个？在我的例子中，我想要的结果是一列中的属性和另一列中的C顶点的@rid。然后，我可以愉快地执行我的小组。聚合。

解决方案

解决它！在OrientDB 2.1中（我正在尝试rc4），有一个叫做 UNWIND 的新子句（参见 SELECT ）。



使用UNWIND我可以这样做：

  SELECT sum（property），groupOn from（
 SELECT property，out（'references'）as groupOn 
 FROM AClass 
 UNWIND groupOn 
）WHERE groupOn.out（'definedBy'）= F 
 GROUP BY groupOn 
  

它可能是一个缓慢的函数，取决于AClass的顶点数及其引用，如果我发现任何性能问题，我会报告回来。

I need to perform an grouped aggregate on a property of vertices of a certain class, the group by field is however a vertex two steps away from my current node and I can't make it work.

My case: The vertex A contains the property I want to aggregate on and have n number of vertices with label references. The vertex I want to group on is any of those vertices (B, C or D) if that vertex has a defined by edge to vertex F.

A ----references--> B --defined by--> E
  \---references--> C --defined by--> F
   \--references--> D --defined by--> G
     ...

The query I thought would work is:

select sum(property), groupOn from (
    select property, out('references')[out('definedBy').@rid = F] as groupOn from AClass
) group by groupOn

But it doesn't work, the inner statement gives me a strange response which isn't correct (returns no vertices) and I suspect that out() isn't supported for bracket conditions (the reason for the .@rid is that the docs I found stated that only "=" are supported.

out('references')[out('definedBy') contains F] doesn't work either, that returns the out('definedBy') for the $current vertex).

Anyone with an idea how to achieve this? In my example, the result I would like is the property in one column and the @rid of the C vertex in another. Then I can happily perform my group by aggregates.

解决方案

Solved it! In OrientDB 2.1 (I'm trying rc4) there's a new clause called UNWIND (see SELECT in docs).

Using UNWIND I can do:

SELECT sum(property), groupOn from (
  SELECT property, out('references') as groupOn
  FROM AClass
  UNWIND groupOn
) WHERE groupOn.out('definedBy')=F
GROUP BY groupOn

It could potentially be a slow function depending on the number of vertices of AClass and its references, I'll report back if I find any performance issues.

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