Neo4j中节点的计数关系问题

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