Question

我是一个名为Endorphin的服务的联合创始人，该服务使用neo4j来存储社交图数据。我们遇到了问题。

我们认为改进查询将解决问题，但事实证明这不是数据库失败的原因，因为有时它会成功返回，有时会因SyntaxException而失败。我们无法看到导致这种情况发生的原因。通过API发送查询会导致查询失败，而当我们使用控制台发送相同的查询时，它们可以很好地工作。

详细说明：

Neo4j版本是1.9.2

我们正在使用Windows Azure，OS Ubuntu 12.04LTS，在JDK7中运行

系统配置是AMD Opteron（tm）处理器4171 HE 8核心CPU，内存14GB，硬盘250 GB + 1TB，数据库大小为1GB。

缓存配置如下：

cache_type=gcr 
use_memory_mapped_buffers=true 
neostore.nodestore.db.mapped_memory=1024M 
neostore.relationshipstore.db.mapped_memory=1024M
neostore.propertystore.db.mapped_memory=2048M
neostore.propertystore.db.strings.mapped_memory=1024M
neostore.propertystore.db.arrays.mapped_memory=1024M

我附上了查询和错误的示例：

查询是：

start n=node(1341474), oldFriend0 = node(21103), 
      oldFriend1 = node(21103), oldFriend2 = node(302) 
create unique n<-[:Comment{CreatedTime:635082180250000000}]-oldFriend0 
create unique n<-[:Comment{CreatedTime:635082713870000000}]-oldFriend1 
create unique n<-[:Comment{CreatedTime:635082527270000000}]-oldFriend2 
return 1.0 as Val

响应状态为：400 Bad Request

Neo4j的回复（可能包含有用的细节！）是：

{"message" : "Can't create UNNAMED1 with properties here. 
It already exists in this context", "exception" : "SyntaxException", "fullname" : "org.neo4j.cypher.SyntaxException", "stacktrace" : 
[ "org.neo4j.cypher.internal.pipes.ExecuteUpdateCommandsPipe$$anonfun$assertNothingIsCreatedWhenItShouldNot$1.apply(ExecuteUpdateCommandsPipe.scala:83)", 
"org.neo4j.cypher.internal.pipes.ExecuteUpdateCommandsPipe$$anonfun$assertNothingIsCreatedWhenItShouldNot$1.apply(ExecuteUpdateCommandsPipe.scala:82)", 
"scala.collection.immutable.Stream.foreach(Stream.scala:547)", 
"org.neo4j.cypher.internal.pipes.ExecuteUpdateCommandsPipe.assertNothingIsCreatedWhenItShouldNot(ExecuteUpdateCommandsPipe.scala

又一个例子：

查询是：

start n=node(1398749), oldFriend0 = node(6856), oldFriend1 = node(6856), 
oldFriend2 = node(6848), oldFriend3 = node(6848), oldFriend4 = node(6848), 
oldFriend5 = node(5600), oldFriend6 = node(7245), oldFriend7 = node(223), 
oldFriend8 = node(223), oldFriend9 = node(223), oldFriend10 = node(223), 
oldFriend11 = node(223), oldFriend12 = node(223), oldFriend13 = node(223), 
oldFriend14 = node(223), oldFriend15 = node(7821), oldFriend16 = node(126899), 
oldFriend17 = node(7133), oldFriend18 = node(7133), oldFriend19 = node(6844), 
oldFriend20 = node(6915) create unique n<-[:Comment{CreatedTime:635094700950000000}]-oldFriend0 create unique n<-[:Comment{CreatedTime:635094783870000000}]-oldFriend1 
create unique n<-[:Comment{CreatedTime:635094735780000000}]-oldFriend2 
create unique n<-[:Comment{CreatedTime:635094744040000000}]-oldFriend3 
create unique n<-[:Comment{CreatedTime:635094744310000000}]-oldFriend4 
create unique n<-[:Comment{CreatedTime:635094776820000000}]-oldFriend5 
create unique n<-[:Comment{CreatedTime:635094730830000000}]-oldFriend6 
create unique n<-[:Comment{CreatedTime:635094731200000000}]-oldFriend7 
create unique n<-[:Comment{CreatedTime:635094742500000000}]-oldFriend8 
create unique n<-[:Comment{CreatedTime:635094742990000000}]-oldFriend9 
create unique n<-[:Comment{CreatedTime:635094743440000000}]-oldFriend10 
create unique n<-[:Comment{CreatedTime:635094743840000000}]-oldFriend11 
create unique n<-[:Comment{CreatedTime:635094744640000000}]-oldFriend12 
create unique n<-[:Comment{CreatedTime:635094749740000000}]-oldFriend13 
create unique n<-[:Comment{CreatedTime:635094826130000000}]-oldFriend14 
create unique n<-[:Comment{CreatedTime:635094748250000000}]-oldFriend15 
create unique n<-[:Comment{CreatedTime:635094708340000000}]-oldFriend16 
create unique n<-[:Comment{CreatedTime:635094742320000000}]-oldFriend17 
create unique n<-[:Comment{CreatedTime:635094742770000000}]-oldFriend18 
create unique n<-[:Comment{CreatedTime:635094692580000000}]-oldFriend19 
create unique n<-[:Comment{CreatedTime:635094743430000000}]-oldFriend20 
return 1.0 as Val

响应状态为：400 Bad Request

The response from Neo4j (which might include useful detail!) was: 
{ "message" : "Can't create UNNAMED1 with properties here. 
It already exists in this context", "exception" : "SyntaxException", 
"fullname" : "org.neo4j.cypher.SyntaxException", 
"stacktrace" : [ "org.neo4j.cypher.internal.pipes.ExecuteUpdateCommandsPipe$$anonfun$assertNothingIsCreatedWhenItShouldNot$1.apply(ExecuteUpdateCommandsPipe.scala:83)",
 "org.neo4j.cypher.internal.pipes.ExecuteUpdateCommandsPipe$$anonfun$assertNothingIsCreatedWhenItShouldNot$1.apply(ExecuteUpdateCommandsPipe.scala:82)", 
"scala.collection.immutable.Stream.foreach(Stream.scala:547)"

感谢任何帮助。提前谢谢。

UPD ：我们正在使用Neo4jClient for C＃来执行查询。它们不会通过控制台失败，但是当使用此驱动程序执行时它们会随机失败。

Answer 1

我会尝试一些可能有用的东西。

您是否尝试过发送一批单独的声明？请参阅：http://docs.neo4j.org/chunked/stable/rest-api-batch-ops.html

通过这种方式，您可以对其进行参数化，并立即将它们全部发送出去：

start n=node({destId}), oldFriend=node({oldFriend})
create unique n<-[:Comment {relProps}]-oldFriend

在params中使用：

{CreatedTime:635094700950000000}

Answer 2

作为参考，此问题将跟踪此问题的进度/结果：https://github.com/neo4j/neo4j/issues/1040

Neo4j返回HTTP 400

2 个答案: