#最慢的版本 match (user:User)-[:WILL_READ]->(book:Book)<-[:HAS_READ]-(user) return book.title, count(user) where 0<=user.id<100
#稍微快一点的版本 match (user:User)-[:WILL_READ]->(book:Book) (book2:Book)<-[:HAS_READ]-(user) return book.title, count(user) where 0<=user.id<100 and book = book2;
百思不得姐呀。
Note：库里的User和Book结点都是百万级别的，所以要分片执行，要是没有id的限制，直接卡死
语句：
profile match (user:User)-[:WILL_READ]->(book:Book), (book2:Book)<-[:HAS_READ]-(user) where user.id>0 and user.id < 20 and book=book2 return book.title, user.id;
用时信息：Cypher version: CYPHER 3.5, planner: COST, runtime: INTERPRETED. 27680 total db hits in 1940 ms.
profile：
耗时的版本在browser里压根就没法运行出来。转shell运行： profile match (user:User)-[:WILL_READ]->(book:Book)<-[:HAS_READ]-(user) where user.id>0 and user.id < 20 return book.title, user.id; ±-------------------------------------------------------------------------------------------+ | Plan | Statement | Version | Planner | Runtime | Time | DbHits | Rows | ±-------------------------------------------------------------------------------------------+ | “PROFILE” | “READ_ONLY” | “CYPHER 3.5” | “COST” | “INTERPRETED” | 1624493 | 0 | 18 | ±-------------------------------------------------------------------------------------------+
±----------------------±---------------±-----±--------±----------±----------------------------------------------------±------------±-----------------------------------------------------------+ | Operator | Estimated Rows | Rows | DB Hits | Cache H/M | Identifiers | Ordered by | Other | ±----------------------±---------------±-----±--------±----------±----------------------------------------------------±------------±-----------------------------------------------------------+ | +ProduceResults | 13 | 18 | 0 | 0/0 | book, user.id, book.title, anon[44], anon[18], user | user.id ASC | 0.0 | | | ±---------------±-----±--------±----------±----------------------------------------------------±------------±-----------------------------------------------------------+ | +Projection | 13 | 18 | 18 | 0/0 | book, user.id, book.title, anon[44], anon[18], user | user.id ASC | 0.0; {book.title : book.title, user.id : cached[user.id]} | | | ±---------------±-----±--------±----------±----------------------------------------------------±------------±-----------------------------------------------------------+ | +Expand(Into) | 13 | 18 | 712393 | 0/0 | cached[user.id], book, anon[44], anon[18], user | user.id ASC | 0.0; (book)<-[anon[44]:HAS_READ]-(user) | | | ±---------------±-----±--------±----------±----------------------------------------------------±------------±-----------------------------------------------------------+ | +Filter | 1051883 | 3852 | 3852 | 0/0 | anon[18], book, cached[user.id], user | user.id ASC | 0.0; book:Book | | | ±---------------±-----±--------±----------±----------------------------------------------------±------------±-----------------------------------------------------------+ | +Expand(All) | 1051883 | 3852 | 3871 | 0/0 | anon[18], book, cached[user.id], user | user.id ASC | 0.0; (user)-[anon[18]:WILL_READ]->(book) | | | ±---------------±-----±--------±----------±----------------------------------------------------±------------±-----------------------------------------------------------+ | +NodeIndexSeekByRange | 37210 | 19 | 20 | 0/0 | cached[user.id], user | user.id ASC | 0.0; :User(id) > { AUTOINT0} AND :User(id) < { AUTOINT1} | ±----------------------±---------------±-----±--------±----------±----------------------------------------------------±------------±-----------------------------------------------------------+
±------------------------------+ | book.title | user.id | ±------------------------------+ 略去结果…… ±------------------------------+
18 rows available after 1 ms, consumed after another 1624492 ms
麻烦大佬们帮忙看看。谢谢了！
explain match (user:User)-[:WILL_READ]->(book:Book), (book2:Book)<-[:HAS_READ]-(user) where user.id>0 and user.id < 20 and book=book2 return book.title, user.id;
explain match (user:User)-[:WILL_READ]->(book:Book)<-[:HAS_READ]-(user) where user.id>0 and user.id < 20 return book.title, user.id;
最让人费解的是，貌似长时间的版本更简单啊，但运行结果偏偏是时间多得离谱。
match (user:User)-[:HAS_READ]->(book:Book) where (user)-[:WILL_READ]->(book) and 0<=user.id<100 return book.title, count(user)
这样试试呢？感觉之前的cypher没有很好的吧之间的变量继承下来