查找没有特定关系的节点 (Cypher/neo4j) [英] Finding nodes that do not have specific relationship (Cypher/neo4j)

问题描述

我有一个具有以下内容的 neo4j 数据库:

I have a neo4j db with the following:

a:Foo
b:Bar

大约 10% 的数据库有 (a)-[:has]->(b)

about 10% of db have (a)-[:has]->(b)

我只需要获取没有这种关系的节点！

I need to get only the nodes that do NOT have that relationship!

以前做 ()-[r?]-() 就完美了！然而，它不再受支持:( 相反，按照他们的建议去做

previously doing ()-[r?]-() would've been perfect! However it is no longer supported :( instead, doing as they suggest a

OPTIONAL MATCH (a:Foo)-[r:has]->(b:Bar) WHERE b is NULL RETURN a

给我一​​个空结果，因为可选匹配需要两个节点都在那里或两个节点都不在那里......

gives me a null result since optional match needs BOTH nodes to either be there or BOTH nodes not to be there...

那么如何获取所有未附加到 b:Bar 的 a:Foo 节点?

So how do i get all the a:Foo nodes that are NOT attached to b:Bar?

注意:数据集有数百万个节点，因此查询需要高效，否则会超时.

Note: dataset is millions of nodes so the query needs to be efficient or otherwise it times out.

推荐答案

那就是

MATCH (a:Foo) WHERE not ((a)-[:has]->(:Bar)) RETURN a;

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