优化 py2neo 的密码插入

Question

我正在使用 py2neo 导入数十万个节点。我创建了一个 defaultdict 来将社区映射到城市。一个动机是更有效地导入这些使用Neo4j's load tool 失败的关系。

因为batch documentation 建议避免使用它，所以我偏离了this post 的OP 之类的实现。相反，文档建议我使用 Cypher。但是，我喜欢能够从我创建的 defaultdict 创建节点。另外，正如first link 演示的那样，我发现导入这些信息太困难了。

为了降低导入速度，我应该创建一个Cypher transaction（并且每 10,00 提交一次）而不是下面的循环吗？

for city_name, neighborhood_names in city_neighborhood_map.iteritems():
     city_node = graph.find_one(label="City", property_key="Name", property_value=city_name)
         for neighborhood_name in neighborhood_names:
              neighborhood_node = Node("Neighborhood", Name=neighborhood_name)
              rel = Relationship(neighborhood_node, "IN", city_node)
              graph.create(rel)

我遇到了超时，当我执行以下操作时它似乎很慢。即使我将事务分解为每 1000 个社区提交一次，它的处理速度仍然非常缓慢。

tx = graph.cypher.begin()
statement = "MERGE (city {Name:{City_Name}}) CREATE (neighborhood { Name : {Neighborhood_Name}}) CREATE (neighborhood)-[:IN]->(city)"
for city_name, neighborhood_names in city_neighborhood_map.iteritems():
    for neighborhood_name in neighborhood_names:
        tx.append(statement, {"City_Name": city_name, "Neighborhood_Name": neighborhood_name})
tx.commit()

保存指向每个城市的指针会很棒，所以我不需要每次合并时都查找它。

Answer 1

在两次运行中执行此操作可能会更快，即首先CREATE所有节点具有唯一约束（应该非常快），然后CREATE第二轮中的关系。

首先使用约束，使用标签City 和Neighborhood，稍后使用更快的MATCH：

graph.schema.create_uniqueness_constraint('City', 'Name')
graph.schema.create_uniqueness_constraint('Neighborhood', 'Name')

创建所有节点：

tx = graph.cypher.begin()

statement = "CREATE (:City {Name: {name}})"
for city_name in city_neighborhood_map.keys():
    tx.append(statement, {"name": city_name})

statement = "CREATE (:Neighborhood {Name: {name}})"
for neighborhood_name in neighborhood_names: # get all neighborhood names for this
    tx.append(statement, {name: neighborhood_name})

tx.commit()

现在的关系应该很快（由于约束/索引，很快MATCH）：

tx = graph.cypher.begin()
statement = "MATCH (city:City {Name: {City_Name}}), MATCH (n:Neighborhood {Name: {Neighborhood_Name}}) CREATE (n)-[:IN]->(city)"
for city_name, neighborhood_names in city_neighborhood_map.iteritems():
    for neighborhood_name in neighborhood_names:
        tx.append(statement, {"City_Name": city_name, "Neighborhood_Name": neighborhood_name})

tx.commit()