Question

我一直在尝试使用Cypher加载一组CSV文件来构建VMware的运行状态视图。我能够执行以下查询：

LOAD CSV WITH HEADERS FROM 'file:///Users/rmorgan/Downloads/All_vm_hierrachy.csv' as csvline
with csvline
where csvline.type = 'VirtualMachine'
MERGE (host:HostSystem { name: csvline.hostid, description: csvline.hosttype })
MERGE (pool:ResourcePool { name: csvline.resourcePool})
MERGE (parent:Folder { name: csvline.parentid, description: csvline.parenttype })
MERGE (vm:VirtualMachine { name: csvline.moid, description: csvline.name })
CREATE (host)-[:HAS_VM]->(vm)
CREATE (vm)-[:HAS_PARENT]->(parent)
CREATE (vm)-[:HAS_RESOURCEPOOL]->(pool);

这会加载有关主机的详细信息，我找到匹配的主机对象，然后使用SET添加更多属性。

LOAD CSV WITH HEADERS FROM 'file:///Users/rmorgan/Downloads/All_vm_hierrachy.csv' as csvline
with csvline
where csvline.type = 'HostSystem' and csvline.parenttype = 'ClusterComputeResource'
match (h:HostSystem {name:csvline.moid})
set h.fullName = csvline.name
merge (p:ClusterComputeResource {name: csvline.parentid, type: csvline.parenttype})
CREATE (p)-[:HAS_CHILD]->(h);

两个查询都加载相同的文件，但实例化不同的对象。有没有办法将它们结合起来？我想在那里写一个CASE声明：

LOAD CSV WITH HEADERS FROM 'file:///Users/rmorgan/Downloads/All_vm_hierrachy.csv' as csvline
with csvline
CASE csvline.type = 'HostSystem' 
   // create some objects and add attributes
CASE csvline.type = 'VirtualMachine'
   // create some objects and add other attributes
END
// create some common objects / attributes irrespective of the path above

我还希望将这些嵌套以生成更复杂的执行路径

LOAD CSV WITH HEADERS FROM 'file:///Users/rmorgan/Downloads/All_vm_hierrachy.csv' as csvline
with csvline
CASE csvline.type = 'HostSystem' 
   // create host object
   CASE csvline.parenttype = 'ClusterComputeResource'
   // create ClusterComputeResource object, link to host
   CASE csvline.parenttype = 'ComputeResource'
   // create ComputeResource object, link to host
CASE csvline.type = 'VirtualMachine'
   // create some objects and add other attributes
END
// create some common objects / attributes irrespective of the path above

Cypher有可能吗？命令似乎存在，但我不能让它们一起工作。

Answer 1

酷用例。

在您合并的唯一属性上创建索引
- 例如create index on :HostSystem(name);
不要在多个属性上使用合并，尤其是在进口
- e.g。 MERGE (host:HostSystem { name: csvline.hostid }) ON CREATE SET host.description= csvline.hosttype

关于你的第二个问题：

我们正在考虑添加条件更新功能
有一种解决方法
保持你的陈述更简单将使他们更快

我目前正在撰写有关此内容的博客文章，目前尚未完成，随便看看并应用提示： https://dl.dropboxusercontent.com/u/14493611/load_csv_with_success.adoc

ESP。 Eager 加载的部分，如果您有很多数据，可能会对您产生影响。

解决方法是，使用filter和foreach的组合来创建＆＃34;工作项的单个或零元素集合＆＃34;

LOAD CSV WITH HEADERS FROM 'file:///Users/rmorgan/Downloads/All_vm_hierrachy.csv' as csvline
with csvline
foreach (line in 
   filter(x in [csvline] where x.type = 'HostSystem' 
                           and x.parenttype = 'ClusterComputeResource') 
   | MERGE (h:HostSystem {name:line.moid}) 
     SET h.fullName = csvline.name
     MERGE (p:ClusterComputeResource {name: csvline.parentid}) 
       ON CREATE  SET p.type= csvline.parenttype
     CREATE (p)-[:HAS_CHILD]->(h)
)

CASE ... WHEN THEN ELSE END是一个表达。

Cypher查询加载复杂的CSV文件

1 个答案: