cypher 2.0:使用基于标签的索引来搜索一组节点 [英] cypher 2.0 : using label based index to search a set of nodes

问题描述

我有它们属于的users和groups. 我有一个索引n:Group(name)

I have users and groups they belong to. I have an index n:Group(name)

我要搜索属于一组组的所有用户:["gr1"，"gr2"，"gr3"]

I want to search for all users belong to a set of groups : ["gr1","gr2","gr3"]

它们属于哪个其他组.

所以我有以下查询: 查询:

so I have the following query: Query :

MATCH (gr:Group) <--(us:User)--(gr2:Group)
WHERE gr.name in ["gr1","gr2"]
return distinct gr2

这里的事情是，我认为cypher不使用索引，因为查询速度很慢.

The thing here, is that I think that cypher don't use the index because the query is to slow.

我有2k个节点，有50k个关系. 以下查询需要200到700毫秒(取决于缓存):

I have 2k nodes, 50k relationships. The following query takes between 200 to 700 ms (depending on cache):

MATCH (gr:Group) <--(us:User)--(gr2:Group)
WHERE gr.name = "gr1"
return distinct gr2

但是，以下查询需要2到6秒钟！

However, the following query, takes between 2 to 6 seconds!

MATCH (gr:Group) <--(us:User)--(gr2:Group)
WHERE gr.name in ["gr1"]
return distinct gr2

当我尝试做时:

MATCH (gr:Group) <--(us:User)--(gr2:Group)
using index gr:Group(name)
WHERE gr.name in ["gr1"]
return distinct gr2

我收到以下错误:

Cannot use index hint in this context. The label and property comparison must be specified on a non-optional node
Label: `Group`
Property name: `name`

(用"="代替"in"，我没有收到错误)

(with "=" instead of "in" I get no error)

我正在使用neo4j enterprise 2.0.1.测试结果来自在neo4j浏览器上运行.

I'm using neo4j enterprise 2.0.1 . The test results are from running on the neo4j browser .

推荐答案

当您在(gr:Group {name: "gr1"})中指定模式中的属性或调用WHERE gr.name = "gr1"时，将引用索引.如果可能有多个attrib值，则可以使用OR子句.

The index is referred either when you specify the attribs in the pattern as in (gr:Group {name: "gr1"}) or you call WHERE gr.name = "gr1". In your case where multiple attrib values are possible you can use OR clause.

MATCH (gr:Group) <--(us:User)--(gr2:Group)
WHERE gr.name="gr1" OR gr.name="gr2"
return distinct gr2

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