如何在含Source、Destination节点的图中查找指向各目标节点的符合要求的路径

你可以通过图查询语言Cypher实现该需求，具体逻辑分为两步：先统计每个Destination节点对应所有入路径的最大长度，再过滤出长度小于该最大值的路径即可。

单目标Destination节点查询（以示例中节点J为例） #

MATCH path = (source:Source)-[:FEEDS_INTO*]->(dest:Destination {name: 'J'})
WITH dest, collect(path) AS allPaths, max(length(path)) AS maxPathLength
UNWIND allPaths AS path
WHERE length(path) < maxPathLength
RETURN path

全量Destination节点批量查询 #

如果需要一次性查询所有Destination节点的符合要求的路径，可以用如下语句：

MATCH path = (source:Source)-[:FEEDS_INTO*]->(dest:Destination)
WITH dest, collect(path) AS allPaths, max(length(path)) AS maxPathLength
UNWIND allPaths AS path
WHERE length(path) < maxPathLength
RETURN dest.name AS destinationName, collect(path) AS validPaths

补充说明：语句中的length(path)返回的是路径包含的关系数量，和常规路径长度计算逻辑一致。如果你的图中Source节点间存在环路，可以给路径匹配添加长度上限避免死循环，比如将[:FEEDS_INTO*]修改为[:FEEDS_INTO*1..10]，可根据你的业务场景调整上限值。

内容的提问来源于stack exchange，提问作者neekitit