Neo4j Cypher查询结构和性能优化

Question

我创建了一个Cypher查询动态构建器。对于复杂的情况，此构建器会生成相当大的查询，例如：

MATCH (parentD)-[:CONTAINS]->(childD:Decision)-[ru:CREATED_BY]->(u:User) 
WHERE id(parentD) = {decisionId} 
MATCH (childD)<-[:SET_FOR]-(filterValue415431:Value)-[:SET_ON]->(filterCharacteristic415431:Characteristic) 
WHERE id(filterCharacteristic415431) = 415431 
WITH filterValue415431, childD, ru, u 
WHERE  ({filterValue4154311} IN filterValue415431.value ) 
 OR ({filterValue4154312} IN filterValue415431.value ) 
 OR ({filterValue4154313} IN filterValue415431.value ) 
 OR ({filterValue4154314} IN filterValue415431.value ) 
 OR ({filterValue4154315} IN filterValue415431.value )  
MATCH (childD)<-[:SET_FOR]-(filterValue415441:Value)-[:SET_ON]->(filterCharacteristic415441:Characteristic) 
WHERE id(filterCharacteristic415441) = 415441 
WITH filterValue415441, childD, ru, u 
WHERE  ({filterValue4154416} IN filterValue415441.value ) 
 OR ({filterValue4154417} IN filterValue415441.value ) 
 OR ({filterValue4154418} IN filterValue415441.value ) 
 OR ({filterValue4154419} IN filterValue415441.value ) 
 OR ({filterValue41544110} IN filterValue415441.value ) 
 OR ({filterValue41544111} IN filterValue415441.value ) 
 OR ({filterValue41544112} IN filterValue415441.value ) 
 OR ({filterValue41544113} IN filterValue415441.value ) 
 OR ({filterValue41544114} IN filterValue415441.value ) 
 OR ({filterValue41544115} IN filterValue415441.value ) 
 OR ({filterValue41544116} IN filterValue415441.value ) 
 OR ({filterValue41544117} IN filterValue415441.value )  
MATCH (childD)<-[:SET_FOR]-(filterValue416273:Value)-[:SET_ON]->(filterCharacteristic416273:Characteristic) 
WHERE id(filterCharacteristic416273) = 416273 
WITH filterValue416273, childD, ru, u 
WHERE  (filterValue416273.value >= {filterValue41627318}) 
 AND (filterValue416273.value <= {filterValue41627319})  
MATCH (childD)<-[:SET_FOR]-(filterValue417410:Value)-[:SET_ON]->(filterCharacteristic417410:Characteristic) 
WHERE id(filterCharacteristic417410) = 417410 
WITH filterValue417410, childD, ru, u 
MATCH (childD)<-[:SET_FOR]-(filterValue416423:Value)-[:SET_ON]->(filterCharacteristic416423:Characteristic) 
WHERE id(filterCharacteristic416423) = 416423 
WITH filterValue416423, childD, ru, u 
WHERE  ({filterValue41642320} IN filterValue416423.value ) 
 OR ({filterValue41642321} IN filterValue416423.value ) 
 OR ({filterValue41642322} IN filterValue416423.value ) 
 OR ({filterValue41642323} IN filterValue416423.value )  
MATCH (childD)<-[:SET_FOR]-(filterValue415673:Value)-[:SET_ON]->(filterCharacteristic415673:Characteristic) 
WHERE id(filterCharacteristic415673) = 415673 
WITH filterValue415673, childD, ru, u 
WHERE  ({filterValue41567324} IN filterValue415673.value ) 
 OR ({filterValue41567325} IN filterValue415673.value ) 
 OR ({filterValue41567326} IN filterValue415673.value ) 
 OR ({filterValue41567327} IN filterValue415673.value ) 
 OR ({filterValue41567328} IN filterValue415673.value ) 
 OR ({filterValue41567329} IN filterValue415673.value ) 
 OR ({filterValue41567330} IN filterValue415673.value ) 
 OR ({filterValue41567331} IN filterValue415673.value ) 
 OR ({filterValue41567332} IN filterValue415673.value ) 
 OR ({filterValue41567333} IN filterValue415673.value ) 
 OR ({filterValue41567334} IN filterValue415673.value ) 
 OR ({filterValue41567335} IN filterValue415673.value ) 
 OR ({filterValue41567336} IN filterValue415673.value ) 
 OR ({filterValue41567337} IN filterValue415673.value ) 
 OR ({filterValue41567338} IN filterValue415673.value ) 
 OR ({filterValue41567339} IN filterValue415673.value ) 
OPTIONAL MATCH (childD)<-[:VOTED_FOR]-(vg:VoteGroup)-[:VOTED_ON]->(c:Criterion) 
WHERE id(c) IN {criteriaIds} 
WITH childD, ru, u, vg.avgVotesWeight as weight, vg.totalVotes as totalVotes 
WITH ru, u, childD , toFloat(sum(weight)) as weight, toInt(sum(totalVotes)) as totalVotes  
ORDER BY  weight DESC 
SKIP 0 LIMIT 10 
RETURN ru, u, childD AS decision, weight, totalVotes, 
 [ (parentD)<-[:DEFINED_BY]-(entity)<-[:COMMENTED_ON]-(comg:CommentGroup)-[:COMMENTED_FOR]->(childD) | 
  {entityId: id(entity),  types: labels(entity), totalComments: toInt(comg.totalComments)} ] AS commentGroups, 
 [ (parentD)<-[:DEFINED_BY]-(c1:Criterion)<-[:VOTED_ON]-(vg1:VoteGroup)-[:VOTED_FOR]->(childD) | 
  {criterionId: id(c1),  weight: vg1.avgVotesWeight, totalVotes: toInt(vg1.totalVotes)} ] AS weightedCriteria, 
 [ (parentD)<-[:DEFINED_BY]-(ch1:Characteristic)<-[:SET_ON]-(v1:Value)-[:SET_FOR]->(childD) | 
  {characteristicId: id(ch1),  value: v1.value, valueType: ch1.valueType, visualMode: ch1.visualMode} ] AS valuedCharacteristics

现在我对表演不满意。例如，对此查询的调用需要~500ms

您能否请一看，看看是否有机会改进此查询？

已更新

这是一个几乎相同的查询，但有不同的参数：

MATCH (parentD)-[:CONTAINS]->(childD:Decision)-[ru:CREATED_BY]->(u:User) 
WHERE id(parentD) = 415406 
MATCH (childD)<-[:SET_FOR]-(filterValue416423:Value)-[:SET_ON]->(filterCharacteristic416423:Characteristic) 
WHERE id(filterCharacteristic416423) = 416423 
WITH filterValue416423, childD, ru, u 
WHERE ('Adobe RGB' IN filterValue416423.value ) OR ('ECI RGB' IN filterValue416423.value )  
MATCH (childD)<-[:SET_FOR]-(filterValue416273:Value)-[:SET_ON]->(filterCharacteristic416273:Characteristic) 
WHERE id(filterCharacteristic416273) = 416273 WITH filterValue416273, childD, ru, u 
WHERE  (filterValue416273.value >= 4) AND (filterValue416273.value <= 53)  
MATCH (childD)<-[:SET_FOR]-(filterValue415431:Value)-[:SET_ON]->(filterCharacteristic415431:Characteristic) 
WHERE id(filterCharacteristic415431) = 415431 WITH filterValue415431, childD, ru, u 
WHERE  ('Compact' IN filterValue415431.value ) 
  OR ('Compact SLR' IN filterValue415431.value ) 
  OR ('Large SLR' IN filterValue415431.value ) 
  OR ('Rangefinder-style mirrorless' IN filterValue415431.value ) 
  OR ('SLR-like (bridge)' IN filterValue415431.value )  
MATCH (childD)<-[:SET_FOR]-(filterValue415441:Value)-[:SET_ON]->(filterCharacteristic415441:Characteristic) 
WHERE id(filterCharacteristic415441) = 415441 WITH filterValue415441, childD, ru, u 
WHERE  ('Brass' IN filterValue415441.value ) 
  OR ('Carbon fiber' IN filterValue415441.value )  
  OPTIONAL MATCH (childD)<-[:VOTED_FOR]-(vg:VoteGroup)-[:VOTED_ON]->(c:Criterion) 
WHERE id(c) IN [415414, 415415, 415412, 415426, 415411]  
WITH childD, ru, u, vg.avgVotesWeight as weight, vg.totalVotes as totalVotes 
WITH ru, u, childD , toFloat(sum(weight)) as weight, toInt(sum(totalVotes)) as totalVotes  
ORDER BY  weight DESC 
SKIP 0 LIMIT 10 
RETURN ru, u, childD AS decision, weight, totalVotes, 
[ (parentD)<-[:DEFINED_BY]-(entity)<-[:COMMENTED_ON]-(comg:CommentGroup)-[:COMMENTED_FOR]->(childD) | 
  {entityId: id(entity),  types: labels(entity), totalComments: toInt(comg.totalComments)} ] AS commentGroups, 
[ (parentD)<-[:DEFINED_BY]-(c1:Criterion)<-[:VOTED_ON]-(vg1:VoteGroup)-[:VOTED_FOR]->(childD) | 
  {criterionId: id(c1),  weight: vg1.avgVotesWeight, totalVotes: toInt(vg1.totalVotes)} ] AS weightedCriteria, 
[ (parentD)<-[:DEFINED_BY]-(ch1:Characteristic)<-[:SET_ON]-(v1:Value)-[:SET_FOR]->(childD) | 
  {characteristicId: id(ch1),  value: v1.value, valueType: ch1.valueType, visualMode: ch1.visualMode} ] AS valuedCharacteristics

Cypher版本：CYPHER 3.1，规划师：COST，运行时间：解释。在390毫秒内总共达到646192 db。

已更新

这是:schema

的输出

Indexes
   ON :Characteristic(lowerName) ONLINE
   ON :CharacteristicGroup(lowerName) ONLINE
   ON :Criterion(lowerName) ONLINE
   ON :CriterionGroup(lowerName) ONLINE
   ON :Decision(lowerName) ONLINE
   ON :FlagType(name) ONLINE (for uniqueness constraint)
   ON :HistoryValue(originalValue) ONLINE
   ON :Permission(code) ONLINE (for uniqueness constraint)
   ON :Role(name) ONLINE (for uniqueness constraint)
   ON :User(email) ONLINE (for uniqueness constraint)
   ON :User(username) ONLINE (for uniqueness constraint)
   ON :Value(value) ONLINE

Constraints
   ON ( flagtype:FlagType ) ASSERT flagtype.name IS UNIQUE
   ON ( permission:Permission ) ASSERT permission.code IS UNIQUE
   ON ( role:Role ) ASSERT role.name IS UNIQUE
   ON ( user:User ) ASSERT user.email IS UNIQUE
   ON ( user:User ) ASSERT user.username IS UNIQUE

已更新

我已根据以下答案优化了查询：

MATCH (parentD)-[:CONTAINS]->(childD:Decision)
WHERE id(parentD) = 415406 
MATCH (childD)<-[:SET_FOR]-(filterValue416423)-[:SET_ON]->(filterCharacteristic416423) 
WHERE id(filterCharacteristic416423) = 416423 
WITH DISTINCT filterValue416423, childD 
WHERE ('Adobe RGB' IN filterValue416423.value ) OR ('ECI RGB' IN filterValue416423.value )  
MATCH (childD)<-[:SET_FOR]-(filterValue416273)-[:SET_ON]->(filterCharacteristic416273) 
WHERE id(filterCharacteristic416273) = 416273 
WITH DISTINCT childD, filterValue416273  
WHERE  (filterValue416273.value >= 4) AND (filterValue416273.value <= 53)  
MATCH (childD)<-[:SET_FOR]-(filterValue415431)-[:SET_ON]->(filterCharacteristic415431) 
WHERE id(filterCharacteristic415431) = 415431 
WITH DISTINCT childD, filterValue415431 
WHERE  ('Compact' IN filterValue415431.value ) 
  OR ('Compact SLR' IN filterValue415431.value ) 
  OR ('Large SLR' IN filterValue415431.value ) 
  OR ('Rangefinder-style mirrorless' IN filterValue415431.value ) 
  OR ('SLR-like (bridge)' IN filterValue415431.value )  
MATCH (childD)<-[:SET_FOR]-(filterValue415441)-[:SET_ON]->(filterCharacteristic415441) 
WHERE id(filterCharacteristic415441) = 415441 
WITH DISTINCT childD, filterValue415441 
WHERE  ('Brass' IN filterValue415441.value ) 
  OR ('Carbon fiber' IN filterValue415441.value )  
  OPTIONAL MATCH (childD)<-[:VOTED_FOR]-(vg:VoteGroup)-[:VOTED_ON]->(c:Criterion) 
WHERE id(c) IN [415414, 415415, 415412, 415426, 415411]  

WITH DISTINCT * MATCH (childD)-[ru:CREATED_BY]->(u:User)  
WITH DISTINCT childD, ru, u, vg.avgVotesWeight as weight, vg.totalVotes as totalVotes 
WITH DISTINCT ru, u, childD , toFloat(sum(weight)) as weight, toInt(sum(totalVotes)) as totalVotes  
ORDER BY  weight DESC 
SKIP 0 LIMIT 10 
RETURN ru, u, childD AS decision, weight, totalVotes, 
[ (parentD)<-[:DEFINED_BY]-(entity)<-[:COMMENTED_ON]-(comg:CommentGroup)-[:COMMENTED_FOR]->(childD) | 
  {entityId: id(entity),  types: labels(entity), totalComments: toInt(comg.totalComments)} ] AS commentGroups, 
[ (parentD)<-[:DEFINED_BY]-(c1:Criterion)<-[:VOTED_ON]-(vg1:VoteGroup)-[:VOTED_FOR]->(childD) | 
  {criterionId: id(c1),  weight: vg1.avgVotesWeight, totalVotes: toInt(vg1.totalVotes)} ] AS weightedCriteria, 
[ (parentD)<-[:DEFINED_BY]-(ch1:Characteristic)<-[:SET_ON]-(v1)-[:SET_FOR]->(childD) | 
  {characteristicId: id(ch1),  value: v1.value, valueType: ch1.valueType, visualMode: ch1.visualMode} ] AS valuedCharacteristics

PROFILE输出：

使用DISTINCT childD时，查询的工作速度非常慢，但距离完美

还要好得多

再试一次

PROFILE MATCH (parentD)-[:CONTAINS]->(childD:Decision)
WHERE id(parentD) = 415406 
MATCH (childD)<-[:SET_FOR]-(filterValue416423)-[:SET_ON]->(filterCharacteristic416423)
USING JOIN ON childD
WHERE id(filterCharacteristic416423) = 416423
AND ('Adobe RGB' IN filterValue416423.value ) OR ('ECI RGB' IN filterValue416423.value )
WITH DISTINCT childD
MATCH (childD)<-[:SET_FOR]-(filterValue416273)-[:SET_ON]->(filterCharacteristic416273) 
USING JOIN ON childD
WHERE id(filterCharacteristic416273) = 416273 AND (filterValue416273.value >= 4) AND (filterValue416273.value <= 53)
WITH DISTINCT childD  
MATCH (childD)<-[:SET_FOR]-(filterValue415431)-[:SET_ON]->(filterCharacteristic415431) 
USING JOIN ON childD
WHERE id(filterCharacteristic415431) = 415431
AND ('Compact' IN filterValue415431.value ) 
  OR ('Compact SLR' IN filterValue415431.value ) 
  OR ('Large SLR' IN filterValue415431.value ) 
  OR ('Rangefinder-style mirrorless' IN filterValue415431.value ) 
  OR ('SLR-like (bridge)' IN filterValue415431.value )
WITH DISTINCT childD
MATCH (childD)<-[:SET_FOR]-(filterValue415441)-[:SET_ON]->(filterCharacteristic415441) 
USING JOIN ON childD
WHERE id(filterCharacteristic415441) = 415441
AND ('Brass' IN filterValue415441.value ) 
  OR ('Carbon fiber' IN filterValue415441.value )  

OPTIONAL MATCH (childD)<-[:VOTED_FOR]-(vg:VoteGroup)-[:VOTED_ON]->(c:Criterion) 
WHERE id(c) IN [415414, 415415, 415412, 415426, 415411]  

WITH DISTINCT * MATCH (childD)-[ru:CREATED_BY]->(u:User)  
WITH DISTINCT childD, ru, u, vg.avgVotesWeight as weight, vg.totalVotes as totalVotes 
WITH DISTINCT ru, u, childD , toFloat(sum(weight)) as weight, toInt(sum(totalVotes)) as totalVotes  
ORDER BY  weight DESC 
SKIP 0 LIMIT 10 
RETURN childD

Answer 1

你的查询的主要问题是你基本上做了很多检查，行是狂野的。因此，这里有一些提示可以减少每个MATCH生成的行数。

1）除非你需要重复，否则使用WITH DISTINCT而不是WITH。 WITH可以创建重复的行（因为您只剪切了一列），并且您处理的每个重复行都是浪费时间和额外的数据库命中。 （即，您删除的每个过滤器列都会添加重复的行）

2）：Value.value重载。它没有语义含义，并且该值甚至不能保证为任何类型。这意味着每一个：价值检查必须走出去触摸一堆：与您搜索的内容无关的值节点。因此，当附加的数量：值节点增加时，找到正确的节点就越昂贵（如果可以将其编入索引，这会更便宜，因此它可以找到正确的：值，并查看它连接到的是什么如果您无法更改您正在使用的架构，并且通过架构，我的意思是如何设置数据/关系，这无济于事。

3）只检查您需要检查的内容。说（a：A） - [：TO] - ＆gt;（b：B）似乎更有效，但如果所有[：TO]都来自：A到：B，Neo4j现在必须验证第一个节点是：A，第二个节点是：B。 Cypher不知道什么是隐含的，所以它必须进行检查，但是这些冗余检查中的每一个都必须熄灭并且每行都按DB。所以最好说（a） - [：TO] - ＆gt;（b）。

4）限制变量范围。在这里，您在开头匹配 - [ru：CREATED_BY] - ＆gt;（u：用户），但不要使用它直到结尾，没有过滤器。这会使每个决定的行数乘以 - [ru：CREATED_BY] - ＆gt;（u：用户），并且必须在进一步的匹配中检查ALL。除非 - [ru：CREATED_BY] - ＆gt;（u：用户）以某种方式极大地限制了匹配的决策（或每个决策只能有一个），最后匹配此支持信息。

5）订购过滤器从最强到最弱（如果可以的话）。尽可能早地减少行数。

6）尽量减少行数。拉出的每一行使得查询中的以下步骤必须更加困难，因此最小化查询中的行。如果您使用OR来组合不相关但相似的列查询（例如条件A或具有条件B的组织的所有组织），并且两个查询的工作只会使另一半的事情变得更加昂贵，那么使用UNION可能会更好结合更小，更快的查询的结果（UNION可以并行运行直到合并结果）。请注意，[1,2,3]中的WHERE org.id等简单查询仍然比UNION快，因为这项工作都可以在一次查找中完成。

除了工会之外，如果您正在收集未经过筛选的节点，您可以使用collect（列）来减少重复＆＃39;最多为1行，而不是UNWIND（列）作为查询末尾的列，以获取您的行！ （此处引用变量名称列）

7）在1个节点上做了很多过滤器？ Cypher有USING提示！提示USING JOIN ON column告诉Cypher，使用更多的起始叶子并加入它们可能会更有效地进行此匹配。因此，在每次匹配时使用USING JOIN ON childD将告诉Cypher并行执行所有过滤器，并使用所有过滤器的重叠行。请注意，USING只是告诉Cypher＆＃34;相信我，如果我们尝试这样做，这应该会更快＆＃34;如果你错了，这实际上可以使查询更糟。 （尽管使用大型查询更加平行，但USING JOIN应该很有用）

<强>更新
首先，注意node.id =＆＃34;常数＆＃34; AND node.value =＆＃34;常数＆＃34; OR node.id =＆＃34; constant2＆＃34; AND node.value =＆＃34; constant2＆＃34; vs node.value = map [node.id]。第一个查询能够对节点查找进行节点过滤，而后者必须过滤已经查找过的所有节点。如果没有先前对该查找进行过滤，则意味着地图必须拉入所有节点。虽然地图提供了一定程度的（可论证的）简单性/灵活性，但它是过滤节点的效率最低的方法之一。

其次，您现在查询的最大问题是：值超级重载，您无法通过ID查找。 ：值应为关系，或具有索引ID字段，以便您不必触摸ALL＆lt; - [：SET_FOR] - 和 - [：SET_ON] - ＆gt;。使用Join提示我认为至少会使SET_FOR具有更高的优先级，这似乎是两者中效率更高的。

这是我尝试更有效地重写PROFILE查询。 （V1）

MATCH (parentD)-[:CONTAINS]->(childD:Decision)
WHERE id(parentD) = 415406 
MATCH (childD)<-[:SET_FOR]-(filterValue416423)-[:SET_ON]->(filterCharacteristic416423)
USING JOIN ON childD
WHERE id(filterCharacteristic416423) = 416423
WHERE ('Adobe RGB' IN filterValue416423.value ) OR ('ECI RGB' IN filterValue416423.value )
WITH DISTINCT childD
MATCH (childD)<-[:SET_FOR]-(filterValue416273)-[:SET_ON]->(filterCharacteristic416273) 
USING JOIN ON childD
WHERE id(filterCharacteristic416273) = 416273 AND (filterValue416273.value >= 4) AND (filterValue416273.value <= 53)
WITH DISTINCT childD  
MATCH (childD)<-[:SET_FOR]-(filterValue415431)-[:SET_ON]->(filterCharacteristic415431) 
USING JOIN ON childD
WHERE id(filterCharacteristic415431) = 415431
WHERE ('Compact' IN filterValue415431.value ) 
  OR ('Compact SLR' IN filterValue415431.value ) 
  OR ('Large SLR' IN filterValue415431.value ) 
  OR ('Rangefinder-style mirrorless' IN filterValue415431.value ) 
  OR ('SLR-like (bridge)' IN filterValue415431.value )
WITH DISTINCT childD
MATCH (childD)<-[:SET_FOR]-(filterValue415441)-[:SET_ON]->(filterCharacteristic415441) 
USING JOIN ON childD
WHERE id(filterCharacteristic415441) = 415441
WHERE  ('Brass' IN filterValue415441.value ) 
  OR ('Carbon fiber' IN filterValue415441.value )  

OPTIONAL MATCH (childD)<-[:VOTED_FOR]-(vg:VoteGroup)-[:VOTED_ON]->(c:Criterion) 
WHERE id(c) IN [415414, 415415, 415412, 415426, 415411]  

WITH DISTINCT * MATCH (childD)-[ru:CREATED_BY]->(u:User)  
WITH DISTINCT childD, ru, u, vg.avgVotesWeight as weight, vg.totalVotes as totalVotes 
WITH DISTINCT ru, u, childD , toFloat(sum(weight)) as weight, toInt(sum(totalVotes)) as totalVotes  
ORDER BY  weight DESC 
SKIP 0 LIMIT 10 
RETURN ru, u, childD AS decision, weight, totalVotes, 
[ (parentD)<-[:DEFINED_BY]-(entity)<-[:COMMENTED_ON]-(comg:CommentGroup)-[:COMMENTED_FOR]->(childD) | 
  {entityId: id(entity),  types: labels(entity), totalComments: toInt(comg.totalComments)} ] AS commentGroups, 
[ (parentD)<-[:DEFINED_BY]-(c1:Criterion)<-[:VOTED_ON]-(vg1:VoteGroup)-[:VOTED_FOR]->(childD) | 
  {criterionId: id(c1),  weight: vg1.avgVotesWeight, totalVotes: toInt(vg1.totalVotes)} ] AS weightedCriteria, 
[ (parentD)<-[:DEFINED_BY]-(ch1:Characteristic)<-[:SET_ON]-(v1)-[:SET_FOR]->(childD) | 
  {characteristicId: id(ch1),  value: v1.value, valueType: ch1.valueType, visualMode: ch1.visualMode} ] AS valuedCharacteristics