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# 创建海王星 GraphMappingConfig
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您创建的 `GraphMappingConfig` 指定如何将从源数据存储中提取的数据加载到 Neptune 数据库集群中。它的格式根据要加载 RDF 数据还是要加载属性图数据而有所不同。

对于 RDF 数据，您可以使用 W3 [R2RML](https://www.w3.org/TR/r2rml/) 语言，将关系数据映射到 RDF。

如果要加载将使用 Gremlin 查询的属性图数据，则为 `GraphMappingConfig` 创建 JSON 对象。

## GraphMappingConfig RDF/SPARQL 数据布局
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如果您正在使用 SPARQL 加载要查询的 RDF 数据，您可以在 [R2RML](https://www.w3.org/TR/r2rml/) 中编写 `GraphMappingConfig`。`R2RML` 是一种标准 W3 语言，用于将关系数据映射到 RDF。示例如下：

```
@prefix rr: <http://www.w3.org/ns/r2rml#> .
@prefix ex: <http://example.com/ns#> .

<#TriplesMap1>
    rr:logicalTable [ rr:tableName "nodes" ];
    rr:subjectMap [
        rr:template "http://data.example.com/employee/{id}";
        rr:class ex:Employee;
    ];
    rr:predicateObjectMap [
        rr:predicate ex:name;
        rr:objectMap [ rr:column "label" ];
    ] .
```

以下是另一个示例：

```
@prefix rr: <http://www.w3.org/ns/r2rml#> .
@prefix ex: <http://example.com/#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<#TriplesMap2>
    rr:logicalTable [ rr:tableName "Student" ];
    rr:subjectMap   [ rr:template "http://example.com/{ID}{Name}";
                      rr:class foaf:Person ];
    rr:predicateObjectMap [
        rr:predicate ex:id ;
        rr:objectMap  [ rr:column "ID";
                        rr:datatype xsd:integer ]
    ];
    rr:predicateObjectMap [
        rr:predicate foaf:name ;
        rr:objectMap  [ rr:column "Name" ]
    ] .
```

位于 [R2RML：RDB 到 RDF 映射语言](https://www.w3.org/TR/r2rml/)的 W3 推荐提供了语言的详细信息。

## GraphMappingConfig Property-Graph/Gremlin 数据的布局
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与属性图形数据相当的 `GraphMappingConfig` 是一个 JSON 对象，该对象为要从源数据生成的每个图形实体提供映射规则。以下模板显示了此对象中的各个规则的情况：

```
{
  "rules": [
    {
      "rule_id": "(an identifier for this rule)",
      "rule_name": "(a name for this rule)",
      "table_name": "(the name of the table or view being loaded)",
      "vertex_definitions": [
        {
          "vertex_id_template": "{col1}",
          "vertex_label": "(the vertex to create)",
          "vertex_definition_id": "(an identifier for this vertex)",
          "vertex_properties": [
            {
              "property_name": "(name of the property)",
              "property_value_template": "{col2} or text",
              "property_value_type": "(data type of the property)"
            }
          ]
        }
      ]
    },
    {
      "rule_id": "(an identifier for this rule)",
      "rule_name": "(a name for this rule)",
      "table_name": "(the name of the table or view being loaded)",
      "edge_definitions": [
        {
          "from_vertex": {
            "vertex_id_template": "{col1}",
            "vertex_definition_id": "(an identifier for the vertex referenced above)"
          },
          "to_vertex": {
            "vertex_id_template": "{col3}",
            "vertex_definition_id": "(an identifier for the vertex referenced above)"
          },
          "edge_id_template": {
            "label": "(the edge label to add)",
            "template": "{col1}_{col3}"
          },
          "edge_properties":[
            {
              "property_name": "(the property to add)",
              "property_value_template": "{col4} or text",
              "property_value_type": "(data type like String, int, double)"
            }
          ]
        }
      ]
    }
  ]
}
```

请注意，顶点标签的存在意味着在这里创建了顶点，而没有顶点标签则意味着顶点由不同的源创建，而此定义仅添加顶点属性。

以下是员工记录的示例规则：

```
{
  "rules": [
    {
      "rule_id": "1",
      "rule_name": "vertex_mapping_rule_from_nodes",
      "table_name": "nodes",
      "vertex_definitions": [
        {
          "vertex_id_template": "{emp_id}",
          "vertex_label": "employee",
          "vertex_definition_id": "1",
          "vertex_properties": [
            {
              "property_name": "name",
              "property_value_template": "{emp_name}",
              "property_value_type": "String"
            }
          ]
        }
      ]
    },
    {
      "rule_id": "2",
      "rule_name": "edge_mapping_rule_from_emp",
      "table_name": "nodes",
      "edge_definitions": [
        {
          "from_vertex": {
            "vertex_id_template": "{emp_id}",
            "vertex_definition_id": "1"
          },
          "to_vertex": {
            "vertex_id_template": "{mgr_id}",
            "vertex_definition_id": "1"
          },
          "edge_id_template": {
            "label": "reportsTo",
            "template": "{emp_id}_{mgr_id}"
          },
          "edge_properties":[
            {
              "property_name": "team",
              "property_value_template": "{team}",
              "property_value_type": "String"
            }
          ]
        }
      ]
    }
  ]
}
```