Neo4j多个可选匹配查询非常慢

Question

我对neo4j很新颖，而且我很难优化返回大量节点/关系的查询。

下面的查询：

MATCH (u:User)-[:CAN_ADMINISTER]->(cs:CustomerSite) 
WHERE u.id="1234" WITH cs 
MATCH r1=(cs)<-[:AFFECTS_SITE]-(t:Ticket) 
WHERE not(t.status = "COMPLETE") 
OPTIONAL MATCH r2=(t)-[:HAS_EVENTS]->(te:TicketEvent) 
OPTIONAL MATCH r3=(t)-[:CREATED_BY]->(u:User) 
OPTIONAL MATCH r4=(te)<-[:HAS_EVENTS]-(u2:User) 
OPTIONAL MATCH r5=(t)-[:AFFECTS_SITE]->(cs)<-[:HAS_SITE]-(c:Customer) 
RETURN r1, r2, r3, r4, r5 

注意到将近一分钟，为产生〜7000行的用户运行。我试图重新组织它并没有多大用处。以下是目前的配置文件。

什么或许可以帮忙，有什么建议？

Answer 1

我强烈建议根据需要从OPTIONAL MATCHES收集结果，并使用WITH来分解查询并缩小您感兴趣的列，以便在子查询之间保留行。正如问题评论中所解释的，MATCHES和OPTIONAL MATCHES可以建立结果行，这可以使SEEM查询成为快速昂贵的结果行。

例如，我会添加注释来分析原始查询在线：

MATCH (u:User)-[:CAN_ADMINISTER]->(cs:CustomerSite) 
WHERE u.id="1234" WITH cs 
MATCH r1=(cs)<-[:AFFECTS_SITE]-(t:Ticket) 
WHERE not(t.status = "COMPLETE") 
// we have 1 row per User at a CustomerSite 
OPTIONAL MATCH r2=(t)-[:HAS_EVENTS]->(te:TicketEvent) 
// now, 1 row per User @ CustomerSite per TicketEvent 
OPTIONAL MATCH r3=(t)-[:CREATED_BY]->(u:User) 
// the above OPTIONAL MATCH had to iterate over each User/CS/TE row instead of just each distinct TICKET 
OPTIONAL MATCH r4=(te)<-[:HAS_EVENTS]-(u2:User) 
// now, 1 row per User @ CustomerSite per User on each Ticket Event 
OPTIONAL MATCH r5=(t)-[:AFFECTS_SITE]->(cs)<-[:HAS_SITE]-(c:Customer) 
// now, 1 row per User @ CustomerSite per User on each Ticket Event per Customer at each Customer Site 
RETURN r1, r2, r3, r4, r5 

虽然它改变了返回的数据格式，一路上做收集，并订购您可选MATCHES更好，要提高查询速度。这里是你可以做到这一点的一种方法：

MATCH (u:User)-[:CAN_ADMINISTER]->(cs:CustomerSite) 
WHERE u.id="1234" WITH cs 
MATCH (cs)<-[:AFFECTS_SITE]-(t:Ticket) 
WHERE not(t.status = "COMPLETE") 
// should be 1 creator per ticket, so best to do this first 
OPTIONAL MATCH (t)-[:CREATED_BY]->(creator:User) 
OPTIONAL MATCH (cs)<-[:HAS_SITE]-(affectedCustomer:Customer) 
// collection of affected customers for each ticket (and their creator) affecting a customer site 
WITH cs, t, creator, COLLECT(affectedCustomer) as affectedCustomers 
OPTIONAL MATCH (t)-[:HAS_EVENTS]->(te:TicketEvent)<-[:HAS_EVENTS]-(userOnEvent:User) 
WITH cs, t, creator, affectedCustomers, te, COLLECT(userOnEvent) as usersOnEvent 
RETURN cs, t, creator, affectedCustomers, COLLECT({ticketEvent:te, usersOnEvent:usersOnEvent}) as ticketEventsAndUsers 

每一行都将在客户站点，车票的创造者，受影响的用户在网站的集合，门票事件的门票集合的票对应并为事件，该事件的用户。

试试看看性能如何比较。如果它看起来更好，你将不得不改变你如何解析返回的数据，但对于循环或两个无法处理的循环来说，这无关紧要。