如何优化以下 neo4j Cypher 查询

Question

我是 cypher 的新手，并且有以下查询来查找 2 种源类型之间的不匹配（例如）。我相信在语法上查询看起来不错，但是在只有 1,00,000 个节点的数据集上运行需要 1 分钟。我还没有使用关系。有人可以帮助优化查询吗？谢谢。

MATCH (VW_OXSS41:VW_OrderXStatusSummary4{SourceTypeID: "1"}) 
WHERE apoc.date.parse(VW_OXSS41.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss'))>=apoc.date.parse("2020-02-10",'s',('yyyy-MM-dd')) AND apoc.date.parse(VW_OXSS41.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss'))<=apoc.date.parse("2020-02-16",'s',('yyyy-MM-dd'))
WITH VW_OXSS41.IdentifierValue as X
MATCH (VW_OXSS42:VW_OrderXStatusSummary4{SourceTypeID: "2"}) 
WHERE apoc.date.parse(VW_OXSS42.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss'))>=apoc.date.parse("2020-02-10",'s',('yyyy-MM-dd')) AND apoc.date.parse(VW_OXSS42.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss'))<=apoc.date.parse("2020-02-16",'s',('yyyy-MM-dd'))
WITH apoc.coll.disjunction(COLLECT(X), COLLECT(VW_OXSS42.IdentifierValue)) as XX
UNWIND (XX) as YY

更新后的查询和错误：-

WITH apoc.date.parse("2020-02-20",'s',('yyyy-MM-dd')) AS a, apoc.date.parse("2020-02-25",'s',('yyyy-MM-dd')) AS b
       MATCH (x:VW_OrderXStatusSummary4 {SourceTypeID: "2"}) 
       WHERE a <= apoc.date.parse(x.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b
       WITH a, b, COLLECT(x.IdentifierValue) AS X
       MATCH (y:VW_OrderXStatusSummary4 {SourceTypeID: "1"}) 
       WHERE a <= apoc.date.parse(y.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b
       WITH X, COLLECT(y.IdentifierValue) AS Y
       UNWIND apoc.coll.subtract(X,Y) AS XX
       MATCH (z:VW_OrderXStatusSummary4 {SourceTypeID: "2"}) 
       WHERE a <= apoc.date.parse(z.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b
       RETURN XX AS MISMATCHES,MAX(z.TimeStamp);
Variable `a` not defined (line 10, column 7 (offset: 551))
"WHERE a <= apoc.date.parse(z.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b"

像这样解决了上面的错误：-

WITH apoc.date.parse("2020-02-21",'s',('yyyy-MM-dd')) AS a, apoc.date.parse("2020-02-25",'s',('yyyy-MM-dd')) AS b
MATCH (x:VW_OrderXStatusSummary4 {SourceTypeID: "2"}) 
WHERE a <= apoc.date.parse(x.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b
WITH a, b, COLLECT(x.IdentifierValue) AS X
MATCH (y:VW_OrderXStatusSummary4 {SourceTypeID: "1"}) 
WHERE a <= apoc.date.parse(y.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b
WITH X, COLLECT(y.IdentifierValue) AS Y
UNWIND apoc.coll.subtract(X,Y) AS XX
WITH XX, apoc.date.parse("2020-02-20",'s',('yyyy-MM-dd')) AS a, apoc.date.parse("2020-02-25",'s',('yyyy-MM-dd')) AS b
MATCH (z:VW_OrderXStatusSummary4 {SourceTypeID: "2"}) 
WHERE a <= apoc.date.parse(z.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b
AND XX = z.IdentifierValue
RETURN XX AS MISMATCHES,MAX(z.TimeStamp);

正确的预期输出为：-

+---------------------------------------------+
| MISMATCHES          | TIMESTAMP             |
+---------------------------------------------+
| "W2002201453550218" | "2020-02-21 12:00:16" |
| "W2002201453550222" | "2020-02-21 12:00:16" |
| "W2002201453550223" | "2020-02-21 09:30:36" |
| "W2002201453550224" | "2020-02-21 12:00:16" |
| "W2002201453550226" | "2020-02-21 12:00:16" |
| "W2002201453550227" | "2020-02-21 12:00:16" |
| "W2002201453550237" | "2020-02-21 12:00:16" |
| "3011WOS002978598"  | "2020-02-21 10:00:54" |
| "3011WOS002978595"  | "2020-02-21 13:00:57" |
| "0010000000006183"  | "2020-02-21 16:00:41" |
| "W2002181111547439" | "2020-02-21 04:00:34" |
| "11"                | "2020-02-21 16:00:41" |
| "10112787861P1458"  | "2020-02-21 10:00:54" |
+---------------------------------------------+

想知道是否有更好的方法？

Answer 1

1. 您需要避免在两个MATCH 子句的结果之间创建cartesian product。假设两个MATCH 子句在它们自己的查询中执行时通常会分别返回N 和M 节点。因为您的查询以它的方式组合了这两个 MATCH 子句，所以您的第二个 MATCH 子句实际上正在执行 N*M 匹配（并生成 N*M 结果行）。

2. 您需要确保已在 :VW_OrderXStatusSummary4(SourceTypeID) 上创建索引。这将优化MATCH 子句执行的查找。

3. 您可以简化 Cypher 代码以避免重复的函数调用。

创建上述索引后，试试这个：

WITH apoc.date.parse("2020-02-10",'s',('yyyy-MM-dd')) AS a, apoc.date.parse("2020-02-16",'s',('yyyy-MM-dd')) AS b
MATCH (x:VW_OrderXStatusSummary4 {SourceTypeID: "1"}) 
WHERE a <= apoc.date.parse(x.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b
WITH a, b, COLLECT(x.IdentifierValue) AS X
MATCH (y:VW_OrderXStatusSummary4 {SourceTypeID: "2"}) 
WHERE a <= apoc.date.parse(y.TimeStamp,'s',('yyyy-MM-dd HH:mm:ss')) <= b
WITH X, COLLECT(y.IdentifierValue) AS Y
UNWIND apoc.coll.disjunction(X, Y) AS YY
...

在第一个WITH 子句中执行COLLECT(x.IdentifierValue) 操作会导致它在单个结果行中返回所有x 节点（而不是N 结果行）。这允许第二个MATCH 避免笛卡尔积问题。