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Neo4j中节点的计数关系问题

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2

sirdan · 技术社区 · 9 年前

每条推特都有一个 topic 属性,该属性定义它所属的主题。

MATCH (h:Hashtag)
RETURN h.text AS hashtag, size( (h)<--() ) AS degree ORDER BY degree DESC

我想为一个主题获取最流行的标签。

MATCH (h:Hashtag)<--(t:Tweet{topic:'test'})
RETURN h.text AS hashtag, size( (h)<--(t) ) AS degree ORDER BY degree DESC

这

MATCH (h:Hashtag)
RETURN h.text AS hashtag, size( (h)<--(t:Tweet{topic:'test'}) ) AS degree ORDER BY degree DESC

而下一个需要很长时间才能运行

MATCH (h:Hashtag), (t:Tweet)
WHERE t.topic='test'
RETURN h.text AS hashtag, size( (h)<--(t) ) AS degree ORDER BY degree DESC

我该怎么办?谢谢

1 回复 | 直到 9 年前

1

2

William Lyon 9 年前

SIZE() 不是聚合(因此您将获得没有group by/aggregation的每一行的模式大小),但是 COUNT()

MATCH (t:Tweet {topic:'test'})-->(h:Hashtag)
RETURN h, COUNT(*) AS num ORDER BY num DESC LIMIT 10

此查询的数量为 Tweet 节点,按分组 Hashtag .