neo4j密码匹配命令串联

这两个Chypher语句是否相同：

//first
match (a)-[r]->(b),b-[r2]->c

//second
match (a)-[r]->(b)
match b-[r2]->c

---

这两个Cypher语句不完全相同。我们可以通过使用来展示这一点，它向您展示了密码引擎将如何执行查询

在以下示例中，查询都以

返回a，c

结束，因为您不能有一个空的

匹配

子句

如您所见，第一个查询具有第二个查询没有的

NOT（r==r2）

过滤器。这是因为Cypher确保单个

MATCH

子句的结果不包含重复的关系

第一个问题

profile match (a)-[r]->(b),b-[r2]->c return a,c;
==> +-----------------------------------------------+
==> | a                     | c                     |
==> +-----------------------------------------------+
==> | Node[1]{name:"World"} | Node[0]{name:"World"} |
==> +-----------------------------------------------+
==> 1 row
==> 2 ms
==> 
==> Compiler CYPHER 2.3
==> 
==> Planner COST
==> 
==> Runtime INTERPRETED
==> 
==> Projection
==>   |
==>   +Filter
==>     |
==>     +Expand(All)(0)
==>       |
==>       +Expand(All)(1)
==>         |
==>         +AllNodesScan
==> 
==> +----------------+---------------+------+--------+----------------+----------------+
==> |       Operator | EstimatedRows | Rows | DbHits |    Identifiers |          Other |
==> +----------------+---------------+------+--------+----------------+----------------+
==> |     Projection |             1 |    1 |      0 | a, b, c, r, r2 |           a; c |
==> |         Filter |             1 |    1 |      0 | a, b, c, r, r2 |   NOT(r == r2) |
==> | Expand(All)(0) |             1 |    2 |      4 | a, b, c, r, r2 | (b)-[r2:]->(c) |
==> | Expand(All)(1) |             2 |    2 |      8 |        a, b, r |  (b)<-[r:]-(a) |
==> |   AllNodesScan |             6 |    6 |      7 |              b |                |
==> +----------------+---------------+------+--------+----------------+----------------+
==> 

配置文件匹配（a）-[r]->（b），b-[r2]->c返回a，c；
==> +-----------------------------------------------+
==>| a | c|
==> +-----------------------------------------------+
==>|节点[1]{name:“World”}节点[0]{name:“World”}|
==> +-----------------------------------------------+
=>1行
=>2毫秒
==> 
==>编译器密码2.3
==> 
==>规划师成本
==> 
==>运行时解释
==> 
==>投影
==>   |
==>+滤波器
==>     |
==>+扩展（全部）（0）
==>       |
==>+扩展（全部）（1）
==>         |
==>+所有节点扫描
==> 
==> +----------------+---------------+------+--------+----------------+----------------+
==>|运算符|估计数drows |行|数据命中数|标识符|其他|
==> +----------------+---------------+------+--------+----------------+----------------+
=>|投影| 1 | 1 | 0 | a、b、c、r、r2 | a；c|
=>|过滤器| 1 | 1 | 0 | a、b、c、r、r2 |非（r==r2）|
==>|扩展（全部）（0）| 1 | 2 | 4 | a、b、c、r、r2 |（b）-[r2:]->（c）|
=>|扩展（全部）（1）| 2 | 2 | 8 | a、b、r |（b）|所有节点都可以| 6 | 6 | 7 |b ||
==> +----------------+---------------+------+--------+----------------+----------------+
==> 

第二个问题

profile match (a)-[r]->(b) match b-[r2]->c return a,c;
==> +-----------------------------------------------+
==> | a                     | c                     |
==> +-----------------------------------------------+
==> | Node[1]{name:"World"} | Node[1]{name:"World"} |
==> | Node[1]{name:"World"} | Node[0]{name:"World"} |
==> +-----------------------------------------------+
==> 2 rows
==> 2 ms
==> 
==> Compiler CYPHER 2.3
==> 
==> Planner COST
==> 
==> Runtime INTERPRETED
==> 
==> Projection
==>   |
==>   +Expand(All)(0)
==>     |
==>     +Expand(All)(1)
==>       |
==>       +AllNodesScan
==> 
==> +----------------+---------------+------+--------+----------------+----------------+
==> |       Operator | EstimatedRows | Rows | DbHits |    Identifiers |          Other |
==> +----------------+---------------+------+--------+----------------+----------------+
==> |     Projection |             1 |    2 |      0 | a, b, c, r, r2 |           a; c |
==> | Expand(All)(0) |             1 |    2 |      4 | a, b, c, r, r2 | (b)-[r2:]->(c) |
==> | Expand(All)(1) |             2 |    2 |      8 |        a, b, r |  (b)<-[r:]-(a) |
==> |   AllNodesScan |             6 |    6 |      7 |              b |                |
==> +----------------+---------------+------+--------+----------------+----------------+

配置文件匹配（a）-[r]->（b）匹配b-[r2]->c返回a，c；
==> +-----------------------------------------------+
==>| a | c|
==> +-----------------------------------------------+
==>|节点[1]{name:“World”}节点[1]{name:“World”}|
==>|节点[1]{name:“World”}节点[0]{name:“World”}|
==> +-----------------------------------------------+
=>2行
=>2毫秒
==> 
==>编译器密码2.3
==> 
==>规划师成本
==> 
==>运行时解释
==> 
==>投影
==>   |
==>+扩展（全部）（0）
==>     |
==>+扩展（全部）（1）
==>       |
==>+所有节点扫描
==> 
==> +----------------+---------------+------+--------+----------------+----------------+
==>|运算符|估计数drows |行|数据命中数|标识符|其他|
==> +----------------+---------------+------+--------+----------------+----------------+
==>|投影| 1 | 2 | 0 | a、b、c、r、r2 | a；c|
==>|扩展（全部）（0）| 1 | 2 | 4 | a、b、c、r、r2 |（b）-[r2:]->（c）|
=>|扩展（全部）（1）| 2 | 2 | 8 | a、b、r |（b）|所有节点都可以| 6 | 6 | 7 |b ||
==> +----------------+---------------+------+--------+----------------+----------------+

---

是的，它们是一样的。哦，知道这一点太棒了，谢谢！我刚刚检查了一下，

（a）-[r]->（b），b-[r2]->c

似乎与

（a）-[r]->（b）-[r2]->c

相同，这很有意义。