了解Neo4j Cypher Profile关键字和执行计划

Question

有人可以解释或提供我们可以了解profile命令的链接,并了解Cypher查询的执行计划以了解优化需求并了解Cypher的工作原理.

例如,我创建了以下Neo4j(版本2.0)示例数据库.

create (ayan:Person{name:"Ayan",age:25}), 
(dixi:Person{name:"Dixi",age:26}), 
(thaggu:Person{name:"Thaggu",age:27}), 
(santosh:Person{name:"Santosh",age:28}),
(ayan)-[:FRIEND]-(santosh),
(ayan)-[:FRIEND]-(dixi),
(thaggu)-[:FRIEND]-(dixi);

现在,当我运行下面的简单查询时,

profile match n:Person, n-[:FRIEND]-m where n.name="Ayan" return m;

我得到以下结果,但我无法理解结果下面的解释. 请帮忙.

+--------------------------------+
| m                              |
+--------------------------------+
| Node[4]{age:28,name:"Santosh"} |
| Node[2]{age:26,name:"Dixi"}    |
+--------------------------------+
2 rows



==> ColumnFilter(symKeys=["n", "m", "  UNNAMED17"], returnItemNames=["m"], _rows=2, _db_hits=0)

==> PatternMatch(g="(m)-['  UNNAMED17']-(n)", _rows=2, _db_hits=0)

==>   Filter(pred="(Property == Literal(Ayan) AND hasLabel(n: Person))", _rows=1, _db_hits=4)

==>     NodeByLabel(label="Person", identifier="n", _rows=4, _db_hits=0)

Answer 1

配置文件信息现在还没有完成,因此没有记录.但是,关键数字是_db_hits,它们不应该特别高,因为它们很昂贵.