我读过很多关于OPTIONAL MATCH和Pattern Comprehesion的评论，但我找不到解决方案。
我的Neo4j数据库中有一个节点（帐户），我想计算属于每个帐户的节点。以下代码适用于一两个可选匹配，但许多可选匹配会产生向量积和超时。
// Account
MATCH (a:Account{billingCountry: "DE", isDeleted: false})
WHERE a.id IS NOT NULL
// User
MATCH (a)<-[:CREATED]-(u:User)
// Contact
OPTIONAL MATCH (a) <-[:CONTACT_OF]- (c:Contact{isDeleted: false})
// Opportunity
OPTIONAL MATCH (a) <-[:OPPORTUNITY_OF]- (o:Opportunity{isDeleted: false, s4sMarked_For_Deletion__C: false})
// Open Opportunity
OPTIONAL MATCH (a)<-[:OPPORTUNITY_OF]-(open:Opportunity{isClosed: false, isDeleted: false})
// Attribute
OPTIONAL MATCH (a) <-[:ATTRIBUTE_OF]- (aa:Attribute_Assignment{isDeleted: false})
// Sales Planning
OPTIONAL MATCH (a) <-[:SALESPLAN_OF]- (s:Sales_Planning)
// Task
OPTIONAL MATCH (a) <-[:TASK_OF]- (t:Task{isDeleted: false})
// Event
OPTIONAL MATCH (a) <-[:EVENT_OF]- (e:Event{isDeleted: false})
// Contract
OPTIONAL MATCH (a) <-[:CONTRACT_OF]- (ct:Contract{isDeleted: false})
RETURN
a.id
u.name AS User_Name,
u.department AS User_Department,
COUNT(DISTINCT c.id) AS Contact_Count,
COUNT(DISTINCT o.id) AS Opportunity_Count,
COUNT(DISTINCT open.id) AS OpenOpp_Count,
COUNT(DISTINCT aa.id) AS Attribute_Count,
COUNT(DISTINCT s.timeYear) AS Sales_Plan_Count,
COUNT(DISTINCT t.id) AS Task_Count,
COUNT(DISTINCT e.id) AS Event_Count,
COUNT(DISTINCT ct.id) AS Contract_Count
我可以用模式压缩重写查询，但是我只是取回数组中的非不同id。有没有一种方法可以计算数组中的不同值，或者另一种方法如何计算模式压缩中的值？
MATCH (a:Account{billingCountry: "DE", isDeleted: false})
WHERE a.id IS NOT NULL
RETURN a.id,
[
[(a)<-[:CONTACT_OF]- (c:Contact{isDeleted: false}) | c.id],
[(a)<-[:OPPORTUNITY_OF]- (o:Opportunity{isDeleted: false, s4sMarked_For_Deletion__C: false}) | o.id],
[(a)<-[:OPPORTUNITY_OF]-(open:Opportunity{isClosed: false, isDeleted: false}) | open.id],
[(a) <-[:ATTRIBUTE_OF]- (aa:Attribute_Assignment{isDeleted: false}) | aa.id],
[(a) <-[:SALESPLAN_OF]- (s:Sales_Planning) | s.timeYear],
[(a) <-[:TASK_OF]- (t:Task{isDeleted: false}) | t.id],
[(a) <-[:EVENT_OF]- (e:Event{isDeleted: false}) | e.id],
[(a) <-[:CONTRACT_OF]- (ct:Contract{isDeleted: false}) | ct.id]
]
如果我在我的第一篇stock overflow帖子中犯了一个正式的错误，我将不胜感激：）
问题在于，在RetURN语句中，因为你在最后计算所有计数，neo4j必须计算笛卡尔积。如果你在每一步计算每个节点计数，它会更优化。像这样：
MATCH (a:Account{billingCountry: "DE", isDeleted: false})
WHERE a.id IS NOT NULL
MATCH (a)<-[:CREATED]-(u:User)
OPTIONAL MATCH (a) <-[:CONTACT_OF]- (c:Contact{isDeleted: false})
WITH a, u, COUNT(DISTINCT c.id) AS Contact_Count,
OPTIONAL MATCH (a) <-[:OPPORTUNITY_OF]- (o:Opportunity{isDeleted: false, s4sMarked_For_Deletion__C: false})
WITH a, u, Contact_Count, COUNT(DISTINCT o.id) AS Opportunity_Count
OPTIONAL MATCH (a)<-[:OPPORTUNITY_OF]-(open:Opportunity{isClosed: false, isDeleted: false})
WITH a, u, Contact_Count, Opportunity_Count, COUNT(DISTINCT open.id) AS OpenOpp_Count
OPTIONAL MATCH (a) <-[:ATTRIBUTE_OF]- (aa:Attribute_Assignment{isDeleted: false})
WITH a, u, Contact_Count, Opportunity_Count, OpenOpp_Count, COUNT(DISTINCT aa.id) AS Attribute_Count
OPTIONAL MATCH (a) <-[:SALESPLAN_OF]- (s:Sales_Planning)
WITH a, u, Contact_Count, Opportunity_Count, OpenOpp_Count, Attribute_Count,COUNT(DISTINCT s.timeYear) AS Sales_Plan_Count
OPTIONAL MATCH (a) <-[:TASK_OF]- (t:Task{isDeleted: false})
WITH a, u, Contact_Count, Opportunity_Count, OpenOpp_Count, Attribute_Count, Sales_Plan_Count, COUNT(DISTINCT t.id) AS Task_Count
OPTIONAL MATCH (a) <-[:EVENT_OF]- (e:Event{isDeleted: false})
WITH a, u, Contact_Count, Opportunity_Count, OpenOpp_Count, Attribute_Count, Sales_Plan_Count, Task_Count, COUNT(DISTINCT e.id) AS Event_Count
OPTIONAL MATCH (a) <-[:CONTRACT_OF]- (ct:Contract{isDeleted: false})
RETURN
a.id, u.name AS User_Name, u.department AS User_Department, Contact_Count,
Opportunity_Count, OpenOpp_Count, Attribute_Count, Sales_Plan_Count,
Task_Count, Event_Count, COUNT(DISTINCT ct.id) AS Contract_Count
